Maradona was at his prime in the 80s, that was a very different time for sports in general, and very much football in particular. You can look at team pictures

Maradona was at his prime in the 80s, that was a very different time for sports in general, and very much football in particular. You can look at team pictures from back then and now and bodies have been way refined. An other component is that natural talent and skill can compensate for a lot of hard work. Not all, but a lot.