Experience-dependent brains get boosts by life-long learning and being socially active, among other acitivites

Not only do our brains sprout new neurons based on experiences we have (via #neurogenesis and #neuroplasticity) but specific activities help protect your brain. This brain growth-protection is based on the "use it or lose it" premises:

1. Never stop learning. 
2. Immerse yourself in another culture. 
3. Seek out tough "stretch" assignments.
4. Manage stress. 
5. Have lots of friends. 

I'll add to this list, exercise, seek novelty in new experiences, and have fun!

http://management.fortune.cnn.com/2013/08/08/5-ways-to-protect-your-brain-and-boost-your-career/