My brother came out of college a little over weight and started riding, that was almost 35 years ago. Since then he has held most of the 24-hour ultra marathon course records in the midwest at one time or another. He has competed in three Race Across America's. When he started he was pushing it to do 20 miles. Now he rides at least 50 a night. During the winter he rides the MB unless the snow is too deep, in which case he skis.
The point is that he started out way out of shape, and it was tough. Now he rides daily because he enjoys it.
As for bikes, he rides a Trek. They have stood behind their products, and he has no complaints.