getting back on after months off

I couldn't ride on the road for months due to work and school taking up my time, so I finally got some time, so I got a trainer, yet every time i get on, I get tired so quick. Like really quick, I'm tired. Is there a good training site? Got any tips for starting out again? How long/many miles should I do?

 

get a heart rate monitor and depending on your max hr, just stay around 140-150bpm for 1-2 hours a few times a week for the first month or two. your probably just over doing it (working at higher heart rates)