Here's a question I want you to sit with for a second: how many of your "I'm just tired" afternoons were actually "I'm just thirsty" afternoons?

We tend to blame the afternoon slump on poor sleep, a heavy lunch, or simply getting older. Sometimes that's true! But very often the culprit is far simpler (and far cheaper to fix). We're running low on water.

Now, I don't want this to become one more item on your health checklist. Hydration isn't about chasing perfect biomarkers or optimizing your way to some flawless version of yourself. It's about something much better. It's about showing up with energy and clarity for the people God has entrusted to you. Your spouse. Your kids. Your coworkers. Your parish. The stranger who needs your patience in the checkout line.

Self-mastery for self-gift. That's the whole point. And believe it or not, a glass of water is part of that gift.

A Little Dehydration Goes a Long Way

You don't have to be stranded in the desert for low fluid intake to affect you. The research on mild dehydration is eye-opening.

In a well-designed study of young women, losing just 1.36% of body weight in fluid led to lower vigor, more fatigue, poorer concentration, more headaches, and a sense that tasks were harder than they actually were. That last one gets me. Think about what that means for a mom tackling homework time or a dad walking into a tough conversation at work. Everything feels heavier than it needs to.

A companion study in men found something similar. At about 1.6% fluid loss, participants made more errors on attention tasks, their working memory slowed, and they reported more fatigue and tension.

Here's the good news: it reverses. In a randomized trial, young adults who rehydrated after a stretch of water restriction saw improvements in fatigue, mood, working memory, and processing speed.

And if your vocation involves keeping your body strong (and it does, whether you're carrying toddlers, hauling groceries, or training for a race), the stakes go up. In one study, losing around 2% of body weight in fluid made a 3 km run about 6% slower, even in mild temperatures. Another study found cyclists performed worse when dehydrated even though they felt no thirstier than when fully hydrated. Read that again. Your thirst signal isn't always a reliable early warning system.

Why This Matters for Your Vocation

Saint Francis praised "Sister Water" in his Canticle of the Creatures as useful, humble, precious, and pure. I love that. Water is humble. It doesn't demand attention. But when it's missing, everything suffers.

Your vocation asks a lot of you. Patience. Presence. Focus. Physical stamina. Emotional steadiness. Every one of those draws on a body and a brain that are made largely of water.

When you're under-hydrated, you're not just a little thirsty. You're more irritable, more foggy, and more tired than you need to be. And the people around you feel it.

So when I encourage you to drink more water, I'm not asking you to obsess over your body. I'm inviting you to steward it, so you can pour yourself out more fully for others.

"But Doesn't My Coffee Count?"

I get this question all the time, and the honest answer is yes. Other sources count!

Researchers commonly estimate that food provides roughly 20 to 30% of our total water intake (think fruits, vegetables, soups, even oatmeal and rice). U.S. national survey data show food moisture making up a little over a fifth of daily water, with the rest coming from plain water and other beverages.

And your morning coffee isn't the dehydrating villain it's been made out to be. In a randomized trial comparing thirteen common drinks, coffee, tea, sparkling water, orange juice, and even cola were no different from still water in how much fluid the body held onto over four hours. Milk actually outperformed water! Another trial found black tea hydrated just as well as water, and a separate study found moderate amounts of caffeine had no meaningful effect on fluid retention.

So breathe easy. Your soup, your salad, and your cup of tea are all pitching in.

So Why Focus on Water?

If everything counts, why do our coaches still point clients toward plain water? A few reasons.

First, people who drink less don't automatically make up the difference by eating more water-rich foods. Low drinkers tend to stay low. The biggest factor in how much water someone takes in is simply how much they drink.

Second, not all fluids come with the same baggage. Data from U.S. adults showed that plain water and water from food tracked with better vitamin and mineral intake, while water from other beverages often didn't. Sodas, sweetened coffee drinks, and juices bring sugar and calories along for the ride.

Third, water is simple. And simple is sustainable.

Your Daily Target

Here's the guideline I give: do your best to drink about half of your goal body weight in ounces of water each day. If your goal weight is 160 pounds, that's around 80 ounces. If it's 200 pounds, aim for around 100.

Why goal weight instead of current weight? Because we build habits for the person we're becoming, not just the person we are today.

Think of this as your foundation. The food and other drinks you enjoy are a bonus on top, not a replacement. (And if you have a kidney or heart condition, check with your doctor about the right target for you.)

A few ways to make it happen:

• Drink 16 to 20 ounces first thing in the morning, before your coffee
• Keep a water bottle with ounce markings within arm's reach all day
• Pair a glass of water with something you already do (every meal, every prayer time, every school pickup)
• Add more on days you sweat heavily, train hard, or spend time in the heat

A Small Act of Love

Drinking water won't make headlines. But it's one of those quiet, ordinary disciplines that makes extraordinary self-gift possible. Every glass is a small yes to being fully present for the people God has placed in your life.

‍

References

1. Armstrong, L. E., et al. (2012). Mild dehydration affects mood in healthy young women. The Journal of Nutrition. https://doi.org/10.3945/jn.111.142000

2. Ganio, M. S., et al. (2011). Mild dehydration impairs cognitive performance and mood of men. British Journal of Nutrition. https://doi.org/10.1017/S0007114511002005

3. Zhang, J., et al. (2021). Effects of water restriction and supplementation on cognitive performances and mood among young adults in Baoding, China: A randomized controlled trial (RCT). Nutrients. https://doi.org/10.3390/nu13103645

4. Funnell, M. P., et al. (2023). Exercise-induced hypohydration impairs 3 km treadmill-running performance in temperate conditions. Journal of Sports Sciences. https://doi.org/10.1080/02640414.2023.2259728

5. Adams, J. D., et al. (2018). Dehydration impairs cycling performance, independently of thirst: A blinded study. Medicine & Science in Sports & Exercise. https://doi.org/10.1249/MSS.0000000000001597

6. Guelinckx, I., et al. (2016). Contribution of water from food and fluids to total water intake: Analysis of a French and UK population surveys. Nutrients. https://doi.org/10.3390/nu8100630

7. Vieux, F., et al. (2020). Trends in tap and bottled water consumption among children and adults in the United States: Analyses of NHANES 2011–16 data. Nutrition Journal. https://doi.org/10.1186/s12937-020-0523-6

8. Maughan, R. J., et al. (2016). A randomized trial to assess the potential of different beverages to affect hydration status: Development of a beverage hydration index. The American Journal of Clinical Nutrition. https://doi.org/10.3945/ajcn.115.114769

9. Ruxton, C. H. S., & Hart, V. A. (2011). Black tea is not significantly different from water in the maintenance of normal hydration in human subjects: Results from a randomised controlled trial. British Journal of Nutrition. https://doi.org/10.1017/S0007114511000456

10. Maughan, R. J., et al. (2019). Sucrose and sodium but not caffeine content influence the retention of beverages in humans under euhydrated conditions. International Journal of Sport Nutrition and Exercise Metabolism. https://doi.org/10.1123/ijsnem.2018-0047

11. Yang, M., et al. (2014). Consumptions of plain water, moisture in foods and beverages, and total water in relation to dietary micronutrient intakes and serum nutrient profiles among US adults. Public Health Nutrition. https://doi.org/10.1017/S136898001400007X

‍