I am delighted to be here too!! I felt the same way...that I would never "fit in" and never be regarded as a "serious bike rider". I'm 41 years old, 5'10" tall, and 220 pounds, and I don't even really have a proper bike to "seriously ride"!! My bike is a moutain bike with hybrid tires, so the wheels are smaller, and the bike is HEAVY. I mean HEAVY! I can't go for miles and miles. I am very eager to get a lighter weight road bike, but just can't afford it for now. So, my daily 10-mile rides, I think, are probably equal to 15 miles on a road bike. Everything is just more work on a smaller, heavy bike.
But I feel the same way as you all do...I need to stay in shape and stay healthy. Two of my children have autism and Tourette's Syndrome, so i need to be around for a long time to care for them. Biking is my therapy. I can clear my head, not worry so much about the future, and just focus on one mile at a time. Yes, other bikers (if there were any around here!) would fly by me, many times over, but I don't care! There's nothing like biking...nothing in the world!