Workrate and Natural Fitness

Hello!
My managerial philosophy is Gegenpressing. I also like developing players from my youth academy and integrating them into the first team. My question is: How do you train Work-rate and Natural Fitness? These are key attributes in my philosophy and most of the time my youth players only gain a +1. any help would be appreciated

They can both be increased from endurance based training. You can also use resistance based training to improve work rate.

Thank you, I was wondering the same.