Warning: The next sentence will likely make you feel old. This week marks 20 years since the first episode of Sabrina the Teenage Witch aired on ABC. (Hey, we warned you!) We caught up with the beloved show’s leading lady, Melissa Joan Hart, at the LiveHealth Online Summit, to find out how she stays healthy these days despite a hectic schedule as an actor-slash-director-slash mom of three. Here, Hart's simple but crucial tips for anyone who's no longer a teen (or teen sorcerer).

Prioritize shuteye

Hart's motto: "work hard, play hard, sleep hard." A few years ago, she decided to invest in a good mattress, a high-quality pillow, and some really nice sheets. "I decided 'I'm an adult now, I need those things, I need a good night's rest!'"

Keep moving (even when you really don't want to)

The older she gets, Hart admits, the more challenging it is to stay motivated to work out. “If you start feeling beaten up—maybe you feel achy or you've gained some weight—you’re less likely to want to go to the gym. But it’s important to counterbalance that.” Whenever you’re hexed by sluggishness, Hart suggests pushing yourself out the door. Down some water and hit the pavement, she says, “or at least start with a walk, and see if it turns into a jog!”

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Fuel right

One key piece of wisdom she's picked up along the way: Her diet has a major effect on her energy level. “I’m much more driven [now] to eat healthy because I want to feel good,” she says. To fuel up when she’s on the go, Hart always keeps nutritious options (like almonds and pieces of fruit) on hand. She also takes probiotics every day. And, most importantly, she says, she drinks a lot of water

Hart believes a healthy lifestyle starts with your dietary decisions: "It’s key to make the right food choices that help you feel good, so you can can stay motivated to be healthy and keep feeling good,” she explains. “It creates a pattern.”

Build on good habits

Speaking of patterns, Hart is quick to point out that lifestyle changes don’t happen over night. Sadly, you can't wave a magic wand and get fit; it takes time and dedication: “You don’t want it to just be a fad, because you’ll end up just falling back into bad habits," she says. “Start with one small thing." For example, this week opt to take the stairs instead of the elevator. Then next week, you can try to cut back on added sugar. “You make something a habit after a few times of trying it,” she says. “So eventually you’ll be able to make these lifestyle changes that stick.”