Your greatest regret may not be what failed, but what never received a chance to.

Failure at least gives you an answer. What tends to sit heaviest much later is the thing never attempted, because it stays permanently unresolved and you never find out what would have happened. Attempts, even unsuccessful ones, close the question. Unmade attempts stay open indefinitely.

Name something you have wanted to try and never begun. Reduce it to a version small enough to start this month, and accept that it might not work. Finding out is the point, and it is available almost immediately.