A game makes an arbitrary line matter because everyone has agreed to care about crossing it.

A line on a field matters only because everyone decided it does, and that shared decision is enough to produce real joy, real heartbreak, and real effort. The arbitrariness of the line does not weaken any of it, which is one of the more interesting facts about how people make meaning.

This works in your favour if you use it. Deadlines, thresholds, and markers you invent can be genuinely motivating provided you treat them as real and, better still, get someone else to hold them with you. Meaning does not have to be discovered in something to work. It only has to be agreed on and then honoured.