Seriously - 'difficult training.' It's one thing to push players - it's an entirely different matter to abuse them.
Right or wrong, good or bad, the old days are gone. When I was a student manager for my HS FB team back in the late 60's & early 70's, they would not let the players take water breaks during practice. today, if a coach tried that, he would not only be fired, but there would be lawyers lining up around the block to file lawsuits.
We're not talking about the Marines here. this is not boot camp. It's not life and death. It's football practice. The players' health and well-being has to be considered.
Yeah, you can work players hard. but if it crosses the line into excessive or physically threatening, I maintain you will lose more players than you will help. Again, right or wrong, today's young people are wired differently than they were 40 years ago. The days of the abusive coach are gone, because (most) players won't accept it.