When it comes to keeping your mind sharp, our ancient ancestors were on to something. Florida State psychology professor, Dr. Thomas Joiner says they thrived thanks to a healthy trifecta: They interacted a lot with nature, and with others, and maintained a high level of physical activity. Put all of that together, and it can be calming and invigorating at the same time. And you don’t have to do all 3 separately. For example, invite a friend hiking, fishing, or for a round of golf. You’ll knock out all 3 at once, and be thinking more clearly as a result.