I cycle to work everyday which is 2.8 miles with short mild sloped hills, which i know is no distance what so ever, however i genuinely can not help but push myself as hard as physically possible when doing so, i don't try to go fast but always do, today getting back from work it i felt very sick and it took me 1 hour and 40 mins before i was feeling like i could move. i do not warm up or down for these journeys. also cycling seems to be the only thing im competitive at. i overtook 3 other cyclists this morning at speed and felt guilty later cause i know how much it bugged me when others overtook me.
I love cycling and do regally, I naturally don't seem to push myself like this for long distance, as i manage to keep a steady fast pace and feel great at the other end.

What im asking is, will this sickness feeling eventually go? (i have been cycling to this job every day for 3 months) or is there a way to avoid it?