That's a good point.
I don't feel bad about cheating. I was always aiming for a reduction. If we all managed a 20-30% reduction, it would help.
It would also become a lot easier as businesses would have to cater to these concerns. This is how Germany got so vegetarian-friendly.
In fact, becoming an ascetic would probably be counter-productive. I think a large benefit of publicly caring about the environment is the signaling. You show that (a) it matters (b) it's doable (c) it doesn't ruin your life. Then other people start to believe they can also do it. If you do let it ruin your life, that will serve to dissuade rather than persuade.