Take it easy on the caffeine
You don't have to give up your coffee fix. In fact, having a cup can actually enhance your mental and physical performance. But if you're guzzling down more than that -- or worse, having a sugar-loaded energy drink -- you're overdosing. "A lot of caffeinated beverages have 10 times the amount of caffeine than a cup of coffee," according to Harrison. "Jacking up the central nervous system isn't the same thing as having energy. Real energy comes from food." Instead of crushing another can of nuclear-colored sugar water, try switching to black coffee or green tea.
Put down your cellphone
You don't need an expert to tell you that America (along with most other countries) is addicted to cellphones, but that attachment affects nearly every part of your life. Mostly, it screws up your sleep, thanks to the blue light it emits. Power down anything with a screen one hour before bed. You can set a nightly alarm on your phone -- the irony! -- to keep yourself in check.
Limit packaged foods, and read labels carefully when you can't
Packaged and processed foods are convenient, but that convenience comes at a cost, usually in the form of a bunch of added sugar, salt, and fat. "Knowing where your food comes from and what's in it is way more important than knowing how many calories or fat it has," says Harrison. When you can, try to cook from scratch, or at least choose snacks that don't have a laundry list of ingredients.
Actually use your health insurance
There's a reason you took the responsible job with benefits, so don't waste them. Younger people tend to put off regular checkups because they think they're untouchable. Wait, that's not true?! "A screening can find high blood pressure, diabetes, high cholesterol, and other issues that can be present without us knowing," says Dr. Alison Amsterdam, a physician at NYU Langone Medical Center, who also emphasizes getting a flu shot every fall.
But the biggest unused insurance perk? "When I speak to patients in their 80s and older, the most common regret I hear is that they didn't take better care of their teeth," Dr. Amsterdam says. "Issues in the mouth can alert us to more serious medical conditions. Floss once a day and brush at least twice."