If you want to stay healthy, it's not enough to focus on your body—you have to train your mind as well.

The brain might seem like something we can just leave alone and yet stay healthy, but recent discoveries suggest that the brain can be changed or "rewired" by experience, meaning it's affected by what we do with it. So if you want to keep your mind sharp and healthy for years to come (and maybe even increase your lifespan), here are some easy ways that anyone can train their brain