When it comes to exercise, how you do it matters more than how much you do. In fact, if exercise is performed at a very low level of intensity, you're not going to get much benefit out of it no matter how much of it you do do. Walking is a good example of this.
A feather can never cause callouses on your hand no matter how many times you stroke it over your palms. The stimulus is simply not intense enough. You'd need to use sand paper and rub it hard over your skin. If you scrape your hand too hard or too often however, you remove skin. But just the right amount and in a short time you have stronger, thicker skin.
Lifting light weights and never taking yourself to the point where the exercised muscles aren't pretty taxed won't do you much good. The stimulus is too weak to cause change. Many ask me, "But Fred, c'mon, isn't something better than nothing?" Not if the something is nothing!
Your goal when exercising (if you're human that is), is to spark or ignite a positive tissue remodeling response. And safely of course. Then you let that alteration occur before you do it again. Research is pretty clear that two, fifteen to twenty minute weight lifting sessions a week provides all of the benefits that RT can bestow. And those benefits are vast. Here too.
So don't think you have to exercise all the time in order to be healthy. That's an exercise lie the fitness industry wants you to swallow and it's been swallowed hook, line and sinker by millions!
Now, if your one of those folks that enjoys being very physically active, go for it - with the following caveat: If you get hurt, the damage can be permanent. 25 years of martial arts destroyed my knees. Now I have a partial fake one. It's not what you want. Trust me.
Now, will everyone get injured? I think we all know the answer to that. And I think we all know that's not the point.
Exercise correctly, not chronically.