I have so much more respect for people of any size who are trying to improve their health and fitness than I have for people who are so hung up on their appearance that they won't do anything active lest they might get sweaty or muss up their hair/makeup/clothes or "not act like an adult".
Engaging in physical activity is even more commendable for large people. I read that a PE teacher strapped on heartrate monitors to some of her "lazy" fat students and had a jaw-dropping revelation that the fat kids were near their maximum heartrate even though they appeared to be slacking off and the skinnier kids were outperforming them at moderate heartrates. They were doing the best they could in their current condition, but were so demoralized by the attitudes of their teacher and classmates.
During the Tour de France coverage, the cyclists were doing some steep climbs but the TV showed a feed from a cyclist's heartrate monitor. He was only at 100 bpm -- a level many fat people have just walking slowly. How do you think he would do if you strapped a 50-pound weight vest and some ankle weights on him ?
Some may say bike clothes are just for skinny people; I counter that fat people quite possibly need them more than anybody else. Many of us sweat a lot, overheat, chafe, and need compression and support for comfort while being active. The stretchy wicking fabric is also very friendly for those of us that don't wear a perfect size and have a few lumps and bulges.
Riding a bike where I can say howdy every once in a while on streets with pretty scenery is fun and something I look forward to doing.
Riding an exercise bike in front of the living room TV or riding back and forth in a deserted area is just exercise that's harder to persuade myself to do.