But not enough detail to take any kind of action unless you do a little research.
So here it is in shorter and more useful form:
First, the NYT article:
Take home message: Exercise is good for you and you are probably not able to do enough to harm yourself unless you are an elite athlete.
The minimum recommended level of effort is 7.5 metabolic equivalent hours (We will come back to what this is and how to measure it.)
You gain a benefit from more than the minimum and the peak is somewhere between 3-5 times the minimum.
But don't worry! You can do up to 10 times the minimum without harm.
The journal article where the NYT gets all its facts--which it spreads-out over a lot of verbiage:
Okay, so what is this Metabolic Equivalent Hours (MEH). Simple: An hour of sitting around is 1.0 MEH. There are charts all over the internet of Metabolic Equivalent Time for different activities and effort levels, here is one. If you run at 8 minutes per mile, the MET is 11.8. So for an hour at this pace, this is 11.8 MEH.
Wikipedia on Metabolic Equivalent:
This makes sense, or at least agrees with calorie calculators--which you can find all over the internet. At my age/weight/sex/height and setting of sedentary, I need 1,800 calories per day to maintain my weight. This comes to 75 calories/hour. Other calculators show me burning 867 calories in an hour of 8:00 minute per mile running. 75 into 867 is about 11.6, which is not far from the 11.8 that I got out of a chart. The math works! Or is at least consistent.
Finally, how many times the minimum effort do I do? I run 30 miles/week at 8:00 minutes per mile which takes an even 4 hours. (11.80)(4)/7.5 = 6.3. I am a little above where the benefit ends, but well below where harm begins.