Its common knowledge that exercise is "good" for you. But many like myself, don't particularly enjoy exercising.

How strong is the research showing that exercise extends life? Is there an ideal amount of exercise for someone who has a relatively sedentary lifestyle (e.g., sits in front of a computer for their job and a lot of leisure time spent sitting). If one follows the surgeon general's recommendation and spends 30 minutes a day doing moderate exercise five times a week, will that person extend their life expectancy (in the aggregate) versus one who specifically doesn't exercise? Does this increase in life expectancy offset the time spent exercising/recovering from it? For example, the surgeon general's recommendation (30 minutes a day x 5 times a week) amounts to 162 days per decade of awake time (assuming 8hrs of sleep a day) being spent exercising/recovering from exercise (assuming it takes 30 minutes of preparation/recovery time to exercise 30 minutes). Will a decade of regular exercise in general, extend my life significantly more than 162 days?

What are the other benefits of exercise? (Other than being stronger/more fit/more attractive). How strong is the research on health benefits, sleep benefits, cognitive benefits? Is cardio workout more important than strength training or is a balanced approach better?

(By how strong is the research, I mean, is this textbook stuff with well-understood theoretical foundation, supported by a good deal of experimental evidence, etc. Or is this still actively being researched/debated by mainstream scientists -- e.g., where some maintain that sure you can find a correlation between those who exercise and those who live longer, but that's because the poor/sick/depressed/unhealthy aren't the type to exercise?)