I hit the gym several times a week, which is good for muscle building but doesn’t seem to help with the cardio. I still seem to run out of stamina before I want to and have to stop and let the lungs/heart catch up. SO, have started my warm up routine on the stationary bike at the gym to help with cardio. As for climbing a hill, I’ve found it easier if I stand on the pedals and lean forward slightly; course the right gear still has to be engaged 😉 And then I might still have to stop and push my bike up the rest of the way if it’s too steep or too long for my lungs. As has been stated, I need more saddle time too.