I'm usually in pretty good shape by the end of april from the road bike, but the MTB with the extra weight was just frustrating. I'm usually one of the guys that blasts up the Manhattan Bridge, but I felt like I was going to cough up a lung. I just didn't think all the extra weight was going to impact me as much as it did. I'll be doing some laps of Prospect Park today on my roadie with my newly built lightweight rear wheel and see how it feels by comparison.
One other thing I should note, I am not so young anymore at 55. I should've started doing this about 30 years ago, but you were considered a little crazy if you rode a bike back then to work. I never stopped riding in all this time so being on the bike isn't new to me. Just look at my join date and post count.