I have returned to exercising since November... Average 3 miles per day at 5 incline 3.5 mph. I seem to do fine with that. Yesterday I carried a very heavy desk up a flight of stairs... I became clammy, nauseous and very weak in my legs along with urge to use the bathroom. Later in the day was fine.. Didn t excercise today, however climbed stairs with heavy basket and same results.... Any suggestions.