Based on similar things he's said in many previous interviews, I think you should read "success in life" as "happiness in life", etc: read the quote as something like: A person’s happiness in life is determined by having a high minimum, not a high maximum. If you enjoy something a lot but there are other things which make you miserable, the latter will hold you back. But if almost everything is enjoyable (or at least tolerable) to you, then you’ve got a good life. — see the example from the article where he got uniforms to make toilet-cleaning more fun.

interesting interpretation. I guess, sometimes you need to know the author to understand what they meant more than what they say.

He probably meant an attitude towards life; giving your best effort to even the most mundane task to get the best out of it. That would also elevate your success in what you do best, and your satisfaction in life in general.

the original quote lost its full context and is giving the wrong meaning. knuth is trying to tell us to find joy in the most mundane things we do. he gave the example of cleaning the toilet, which his family does wearing suits.

solving top problems in quantum mechanics is, by any means, no mundane task.

but i have heard similar quotes before. about the joy of doing something being more important than the result. i think it's because joy is so contagious. shared joy makes you even happier, imo.

There is a De-motivational Poster from back in the day with a picture of a skier doing an airborne yard sale. Captioned with 'If you can't learn to do something well, learn to enjoy doing it poorly'

A diamond right there.