Stay committed enough that temporary frustration looks small against the timeline.

Frustration expands to fill the present. It feels total while it is happening, and it is nearly always temporary and small against the actual timeline of what you are building. Holding the timeline in view is what keeps a bad month from ending a good decade.

When frustration peaks, put a number on it. How much of the whole effort is this? Usually a few percent. That does not make it pleasant, and it does put it in proportion.