Be a Lifelong Learner
Yeah, sure, we know what your ideal picture of retirement looks like: One hammock, one baby-blue ocean, four naps a day. That's great and all, but one of the best ways to ensure that your mind doesn't liquidate into the consistency of a pina colada is to continue to give it a reason to function. Work it. Challenge it. Teach it new things.
When you increase your learning during life, you decrease the risk of developing memory-related problems. That means your brain has a fighting chanceif you keep it active and engaged, if you keep challenging it with new lessons, if you learn a new game or new hobby or new vocation. You have to challenge your mindeven making it a little uncomfortable by pushing yourself to learn tasks that may not come naturally. Doing tough tasks reinforces the neural connections that are important to preserving memory. Like a clutch athlete, your mind has a way of rising to the occasion. Challenge it, and it will reward you.