Thanks to all for the encouragement. I go MTN biking with my husband and he is much more experienced. After 4 miles uphill with several breaks, I was just exhausted. I wasn't even enjoying the beautiful scenery on the way up.

Do you take many breaks when you are riding? My husband doesn't seem to need them but I sure do. I need some recovery time.

I am going to spinning classes about 5 days a week to improve my cardio and we MTN bike on the weekends. I commute to work by bike but it's such a short ride that I doubt I'm getting much cardio benefit from it.

I must say that one the way down from the 4 mile uphill I was really impressed that I was able to make it up that far. It was a long way down!