Doing less than you’re capable of eventually becomes something you’re capable of accepting.

Standards drift downward quietly. The first time you settle for a weaker version of your work it registers as a compromise, the tenth time it registers as normal, and after that you are not settling at all because your sense of adequate has moved. Nothing announced the change. Your tolerance simply adjusted to your behaviour.

Find an area where you would once have been dissatisfied and now are not, and ask whether the situation improved or your expectations moved. Be specific and be fair to yourself; sometimes the lower standard was a sensible adjustment. When it was not, restore the bar in one small place and let the rest follow.