We know that our brains are like muscles and we have to keep using and challenging them to increase our memories and recall. People who take classes, do word games, read, etc. will have their wits about them longer than those who don't. The nice thing is today you can learn something new for free, take a day class, trade out services (like learning a new language) on places like Gumtree, or join a club or volunteer. Again, just do it and you will reap the rewards as time goes by. So what are you waiting for? Do it today. Take action. Always take action to move yourself forward!
Personally I'm on a fitness challenge and having my iPad teach me how to play Chess. It's fun and easy.