(I apologize if this is in the wrong place, I'm 200+ so I'd qualify, but still this is more my random musings that hopefully will encourage some newbies - I have no blog but it would be scattershot if I did - I would probably throw this up on a blog in the future if I get one.)
I thought I'd post some of my thoughts on my rides. I started riding about a month ago (a week in the shop), but I started walking about 3 years ago. When I started biking, I struggled with hills and would be gasping for breath at the top of them. Now I'm managing most of them pretty well - and I'm sure all my fitness issues (including weight) can be addressed with time.
Much of riding (as walking), I'm finding is your mind. One of those things is the conception of distance. It's hard when you start to think, "I'm going out to ride 10 miles" (I just made it up to that today without a problem ), or "I'll never be able to make it to work on the bike", and it can shut you down. Driving in a car has a tendency to skew your perceptions of distance as well as your sense of physical ability. One thing I can say is if it seems impossible to do, try it! You might find you can do more than you think!
The key, of course, is your physical endurance - you want to stop when your body says it's time and not when your mind says it's time. When the distance mounts in the mind, the mind can be a enemy to getting there - the idea of it, or the montony of riding for a protracted period can get to you. My walks were like that - I could be out for 2 hrs and just the idea of it at first thought would be "Boring!", but I was eventually able to tune my mind out of the idea after a few trips.
Another one is the idea of taking hills...there was a very hilly road around here and my first thought would be very averse to the idea of taking that road. But again, conception can get to you - try it! I ended up taking that road not once but twice today. The only thing that was keeping me from it was my mind more than my fitness level. If you see something you think you can't take, try it!
Of course, there's always the issue of the fitness level. Working against that can be discouraging for most. But don't give up, what is impossible today is always possible into the future. Don't get discouraged!