Not technical but the self-knowledge of how to put yourself in a productive state. Knowing how to sleep well, eat well, exercise well to allow yourself to perform at a sustained high-level.
Someone may be more technically competent at a problem-space (at the start), but if you are able to work diligently at the problem over a sustained period, you will have 10x better results than those who crash/burnout/lose interest/try to sprint to the finish.
Someone may be more technically competent at a problem-space (at the start), but if you are able to work diligently at the problem over a sustained period, you will have 10x better results than those who crash/burnout/lose interest/try to sprint to the finish.