Exercise Is WAY better for you than you think it is:

First of all....being very physically fit will add a clean 3-5 years on to your lifespan (ie you'll live longer) and increase what doctors call your healthspan by a clean 6-8 years. Some have stated longer. Truly....It's not just "you'll look better" thing.

Source: https://www.natap.org/2011/HIV/081911_03.htm

-Vigorous exercise reduces the risk of Alzheimer's by about 45% and of Dementia by 30%....it's one of the few things you can do prevent the disease

Source: https://www.alzheimers.org.uk/about-dementia/risk-factors-and-prevention/physical-exercise#:~:text=Exercising%20in%20mid%2Dlife&text=Combining%20the%20results%20of%2011,reduced%20by%2045%20per%20cent.

-Vigorous exercise overall cancer risk (excluding possibly skin cancer) by 10-20%...this includes pancreatic and lung cancers.

Source: https://www.cancer.gov/about-cancer/causes-prevention/risk/obesity/physical-activity-fact-sheet

In General...people write off exercise as a way to lose weight...in general it's not so great at that because most people don't exercise enough to outrun their terrible diet. But short of that, it's an incredible boost to just about every aspect of your existence. We're still finding out long-reaching impacts of exercise we didn't know about before.

The more the better. The more consistent the better. The more vigorous the better.

And lastly...the WORSE shape you're in now, the STRONGER the benefits of even a LITTLE exercise are for you. Ironically couch potatoes get more marginal benefit than athletes. The estimate is 10 minutes of vigorous exercise a day will add about 2 years to your life.