1. Exercise 3 hours a week. You’ve experienced it yourself on a mind-clearing walk: Moving your body is freaking great for your brain, both now and years from now. Majid Fotuhi of NeurExpand recommends keeping your heart rate up for at least 20 minutes at a time. In one study, people who increased their three weekly walks from 10 to 40 minutes expanded their hippocampi by 2% after a year—the equivalent of getting 2 to 4 years younger above the neck. Exercise increases levels of brain-derived neurotrophic factor (BDNF), a protein that’s essentially fertilizer for the brain. (Learn more about Fotuhi’s exciting new research on how you can prevent Alzheimer’s.)
  2. Meditate 10 minutes a day. Too much cortisol is hippocampal poison. Basic mindful meditation is an effective weapon against it (as is exercise). Fotuhi trains his patients to start with a simple 5-5-5 routine: Sit up straight, close your eyes, and inhale slowly for a count of 5, then exhale for a count of 5. Do this for 5 minutes. Stay with the count and the movement of your breath, even if your mind wanders. Practice this twice a day—or, if you’re stressed all the time, 3 or 4 daily. MORE: 8 Simple Meditations That Can Change Your Life
  3. Get 1,500 mg of omega-3s daily. People who have higher levels of DHA and EPA (found in fatty fish) also have (surprise!) larger hippocampi. (These 20 delicious salmon recipes will help you up your omega-3s.) MORE: How Science Is Learning To Beat Alzheimer’s At Its Own Game
  4. Memorize something every day. Growing your brain might not be as simple as signing up for Lumosity—in fact, Fotuhi and a host of other neurologists find such arbitrary games to be ineffective—but making a habit of memorizing things will tone your hippocampi. Med students whose hippocampi were measured before and after they prepped for the boards substantially expanded their hippocampi after studying. People who learned to juggle (which is essentially memorization of physical movements) showed an increase in gray matter after 3 months. UCLA neurologist Gary Small recommends cross training, too. “Your brain loves variety,” he says, so challenge it whenever you can. Increased social interaction helps, as does learning a new skill or language.