It seems kind of, duh. But, we can never be reminded enough how important staying hydrated is. Especially when you’re outside in the sun and it’s pushing 90+ in Boston.

Some notes from WebMD:

Choosing Your Hydration Fluid

If you are not running a race, “the rule of thumb is to drink 8 ounces of a sport drink or water possibly every 20 minutes,” says Maharam, who advises the ING New York Marathon. No more, no less. “If you are exercising less than 40 minutes, water is fine, but for anything over 40 minutes, you want a sports drink that has sugar or salt in it because this helps you increase the fluid that goes into the body. Most sports drinks contain the equivalent of an “active pump” that gets more water into the body faster than the unassisted process - simple diffusion of water - would have.

When choosing a sports drink, look for salt and sugar on the label and choose a flavor that you like. While shoppers may be bombarded with vitamin-infused beverages, Maharam says added vitamins are useful for recovery and post-event muscle soreness — not for hydration the day of the event.

Dehydration

Dehydration is somewhat insidious, adds Cohen. You can’t always tell when it’s starting.

“Humans don’t have a ‘fuel gauge’ like your car, so there is no way to tell if you’re full or even approaching empty, and thirst is typically a poor guide,” he says. Early signs of dehydration may include poor concentration, headache, and inability to think clearly.