I live in North St. Louis MO County and ride quite a bit to South County and man it's amazing (IMO) the number hills I get faced with. Though over time I have gotten stronger there are times especially after about 25 miles I do walk my bike up some.

I do believe that it's mental as there have been times when I was at the end of my ride and there is a particular hill that is STEEP and I have rode up it. When I get to the top I literally feel hurt. My chest and legs feel it but cruising slow for a few minutes my body recovers enough to get rid of that uneasy feeling.

Manny