Hey friends -- I have a training / cardio question and a problem that I have been experiencing and hope that some here can relate and / or provide some insight and advice into what might be going on. First, a little bit about myself and my fitness level. I have never been very physically fit and I have never been an athlete; I am 33 years old, weigh 200 pounds. Over the past few years, I have made attempts to work on my fitness level and get 'into shape' and each and every time I try, I get dealt with some very discouraging and frustrating post-exercise symptoms. I have tried running over the past few years -- the first time I tried, I think I may have pushed myself too hard and tried to do too much too fast. The second time, I followed a running regime which started me up very, very slowly over the course of 6 months. I lasted 5 months before giving up. After every run, I would just feel like I had beat up my body -- very exhausted, a lingering, general 'unwell' feeling that would last most of the day. I finally threw in the towel and figured it was the impact and something to do with my physiology and being unfit for running. Now, a year or so later, I am trying cycling. Low impact, low stress, etc. I figured this would be a great exercise and I really had high hopes. What is happening is the same thing: I ride 30-45 minutes, 4-5 times a week -- i'll push myself a bit, but not too much. I will return home and most of the time will just feel terrible. I am unable to sleep / rest, will occasionally feel nauseous on and off throughout most of the day afterwards and just feel run down. This is confusing me because I don't think I'm doing that much exercise to warrant these types of symptoms. Instead of feeling 'good' after a 40 minute ride, I feel like I just beat the **** out of my body for 40 minutes and I don't understand what I'm doing wrong. I don't think hydration is the issue as I drink tons of water all day, every day and during the ride. Is this at all normal? I feel like I'm in the vast minority -- where most people feel great after a cardio workout, I feel sick and what's worse, it tends to last half the day or the entire day! It is possible, I suppose, that diet could be at play -- but I have tried eating, eating light, not eating at all before and after each ride and the results are similar. Could I be doing too much too fast?? Seems unlikely ... I know this sounds odd, but sometimes it really feels like my body is allergic to physical exertion. Any prolonged, consistent cardio regime wears me out. The best way to describe what I'm feeling is 'run down.' Sometimes I think that it's just something I have to 'fight through' but when I try that, it just gets worse. Please help !!! Thanks ! -Mark