i just started workin out again after about 2 years, i went from 220lbs-now at 300lbs, and im 6'3''. im just tryin to hit the cardio and shed pounds before i get back in the gym, i ride a bike in the morning about 2 miles and do 40 yrd wind sprints (4) with 3 min rest between. im eating well, but ive been sick and weak for the rest of the day. will this go away or should i try something else?