“Just do it” from Nike is fine but it seems to be about finishing something you need to finish, not necessarily because you want to finish ("Just do it" is similar to avoiding procrastination). So that isn’t enough. “Don’t not do it” is about doing something you want to do but are afraid (worried because it is different, or maybe slightly embarrassing, or risky, etc). It may be already finished or easy to finish but you are scared. These are the things you need to do. If you purge these mental roadblocks, you will benefit yourself. You will never be “better than the rest” if you don’t allow yourself to complete something because of worry or risk – you will be the rest. Don’t be the rest. Don’t not do it.
"Action is a great restorer and builder of confidence. Inaction is not only the result, but the cause, of fear." [Norman Vincent Peale, author]