I'm not a fat person by any means, but I do carry a fair bit of paint for someone my size and used to carry a rather heavy gun that made me not as able to move as well as someone ordinarily would that looks like me. That pretty much made me a back player for the time being, but then I realized that it was actually giving me an advantage. Instead of making sprints to far forward bunkers and getting shot, I was playing more conservative, staying alive, and paying attention to other aspects of the game. Instead of the mentality at my home field (which in my opinion was a huge factor as to why the field's home team for a number of years stayed mediocre at best and never went anywhere significant where teams of their age and experience are now pro) that everyone should act and think like a hybrid forward-mid and do only what they do, I saw the jobs backs do as what I needed to do because someone needed to and I wanted to. I'm still learning every day I go to a field.
As for speed, endurance is more the issue. It can be a hot, long, humid, mosquito saturated day with every little scrape, cut, bump, bruise, etc. possible all over your body, 350 fps bunkering welts, and crappy calls by refs that got you shot another 20 times after the guy you lit up just beforehand didn't get pulled and you walked past him at about 20 feet. It's about 40% physical toughness and 60% mental toughness...maybe a little more to one or the other depending on where you are. Young and/or athletic people usually have more of both than most of everyone else. I'm somewhat young but nowhere near as athletic as I used to be, though I need to work on that and will.
