A later George Lucas Star Wars movie (one that I have never seen) reportedly has a somewhat-silly but much-quoted line, as Jedi Master Yoda admonishes, "No. Try not. Do, or do not. There is no try." Even with the fractured syntax it's not deep philosophy. Many years ago I read about the Taoist principle wu wei, which literally means "non-doing" or "without action". The notion is probably inexpressible, but what I think it refers to is balance, harmony, and the avoidance of forcing in one's life. That makes sense.
But even better than "not-try" or "not-do" is the mantra "not-care". It reminds me of Richard Feynman's autobiographical collection of anecdotes, titled "What Do You Care What Other People Think?". And maybe "not-care" works best if you say it in Chinese, or with a heavy Brooklyn accent, or when splattered with mud in the midst of a long trail run, or in other such unæsthetic circumstances!