Tennis is not like other sports where the coach is hired by an independent entity and that makes a huge difference in the dynamic.
People may say I developed an iron will but what really happened is that I made myself much fitter. I think an iron will is always supported by fitness.
I just travel all the time. And I was just looking at the schedules now and starting the first week of October I will be every weekend with somebody at tournaments through Christmas. So it gets very difficult to just go away and not do that.