Calisthenics Unity

I am very new at working out but I still do sport anyway, this sport involves a lot of running and cardio in general, in one of Chris' videos he says for an ectomorph it is bad to do cardio on rest days, but I enjoy this sport, is it really that bad?

it's "bad" in terms of gaining muscle mass as you burn more energy. But you could just consume more energy then.

I couldn't agree more. What Chris means by energy is calories. So, on rest days when you do cardio, make sure you eat more, 500 calories more should do the job. Depends on how much volume in cardio you do. Just make sure you eat more.