From what I've seen, between the ramped up training, the hot yoga, and the Dolce diet, Hendricks is paying a lot more attention to fitness and cardio and everything. That said, few can compete on the level of stamina and athleticism that GSP brings to the octagon. Nick Diaz made GSP look a little tired for a fleeting moment, but even he couldn't capitalize, and he's the endurance king at 170. So, while I don't feel too confident in Hendricks being able to capitalize on any errors in the later rounds, especially the championship rounds, hopefully he won't fade either.
Specialization helps different disciplines advance. MMA keeps them practical.