I just got done running tren ace/mast prop/test prop blend... best thing i've ever ran, no endurance problems but i only ran it for 4 weeks. I agree, i believe that tren endurance sufferance is overatted here. I believe that if you are in shape you are in shape, lots of guys that lift are not in shape so it makes it even worse. If anything, play basketball for an hour a day, boom, knocked out your cardio without thinking about it. You have to find something you truley enjoy doing for cardio.. i would never run on a tredmil because i absolutely hate it. Running to me is just the most boring thing even. Sprinting is a little better, and sports are the world. If it really is bothering you that much though, then yeah, i'd suggest not doing cardio, but it can really help your fat loss. Just make sure to get plenty of liquids at least a gallon of water a day and lift hard and you'll be good.