Physical activity doesn't have to be painful or strenuous.

Just get active, often.

“If all individuals were as active as the top 25% of the population, Americans over the age of 40 could live an extra 5.3 years on average.

The greatest gain in lifetime per hour of walking was seen for individuals in the lowest activity quartile where an additional hour’s walk could add 376.3 min (~6.3 hours) of life expectancy”

This is also why it's important to stay healthy and injury free to allow your body to improve your health.

Knee pain can become heart disease if it goes unchecked for too long.

https://bjsm.bmj.com/content/59/5/333