Cardio Kills

I have quit lifting heavy, and started doing my cardio again. Today was my first time running more than a mile in over a month and a half. I couldn’t believe how much it hurt, so after I finished running I went to the pool and I swam a few laps. My lungs were really hating me, and my arms were dead I had to take breaks in between each lap. I know that as long as I keep it up I should be back to where I left off, when I quit doing cardio, in a week or so. I kind of wish I had not quit doing my cardio at all, but I needed to bulk up some and cardio doesn’t help for that. EST tryouts are going to be here soon, and I want to be sure I am prepared for them. I know once I get back to Utah I am going to have to run alot to adjust to the altitude difference, I think it is nealry 4,500 ft higher than here.