I don't have any stamina because I spent the better part of 10 years basically sitting on my butt and not doing anything other than working (mostly retail as a cashier when is basically standing in one spot all day). Another reason I love my current job since as a merchandiser I'm walking and lifting, ect. Also basically had spent probably 15 years or so not riding a bike. (My guess is my candence is slow for that same reason.) My road bike has a triple front rings and I basically ride in the middle front one and the back is somewhere in the middle of those rings as well. I did try an easier ring on the front so spin more, but ended up making it worse to where I got worn out faster. So yeah, I just need to work on the overall of everything. Spent too many years being way too lazy, is where I think the problem is at.