In the most simplest terms your brain function needs stimulation. Out of your five senses: smell, taste, touch, vision and hearing, many doctors feel that hearing is number one. The brain has to determine what that sound is. Voices, doors shutting, golf balls hitting the club literally millions upon millions of sounds 24 hours a day which in turn gives your brain exercise.
As you get older your five senses dull down. As for your sense of touch and smell keep active with strong blood flow. As for taste don’t eat or drink extremely hot food or beverage. To maintain your vision protect your eyes from the sun. If damage has already occurred you may also get glasses or surgery.
For your hearing, stay way from loud noises or wear ear protection. If damage has already occurred you can get hearing devices.
Fun note: The number one brain stimulator is not brain games even though they are good for you, the number one is juggling. Not only is it eye to hand coordination but it is also a physical activity that stimulates blood flow.