Updated: Jan 7, 2020
Their are plenty of reasons to exercise from having more strength, better stamina, increased mobility and an attractive physique. However, the best reason to keep exercise in your daily life should be your cognitive health. The ability to problem solve, make new connections(memories), retrieve information, etc. is dependent on the health of your brain. Within almost every career, your cognitive health determines how well you'll perform.
In a large scale study done by German scientists at the European College of Neuropsychopharmacology analyzing over 1200 MRI brain scans determined those with better physical fitness also performed better on cognitive tests. Specifically those that did better during a physical fitness tests showed in "young healthy adults is associated with better cognitive performance, and with structural integrity of the white matter in the brain: healthy white matter is known to improve the speed and quality of nerve connections in the brain." ( https://www.eurekalert.org ). Furthermore, the team leader of the study Dr. Jonathan Repple stated "It surprised us to see that even in a young population cognitive performance decreases as fitness levels drops. We knew how this might be important in an elderly population which does not necessarily have good health, but to see this happening in 30 year olds is surprising. This leads us to believe that a basic level of fitness seems to be a preventable risk factor for brain health."( https://www.eurekalert.org ). Seems like if you want a better functioning brain, you should forge a healthier body.
There are multitudes of reasons to keep your body healthy, now if you've got one more. If you'd like a better functioning and long lasting brain then get to those push ups and sit ups!
Here's the article if you'd like to read more about the study: https://www.eurekalert.org/pub_releases/2019-09/econ-tfa090919.php