The route drawn confidently may contain a hill its maker has never climbed.

Whoever drew the line has probably not walked the steep part with a bag on their back. That is why it looks smooth in exactly the way their experience of it was, and why certainty about a plan often rises with distance from the work of carrying it out. This is not laziness or arrogance. Nothing in the drawing tells you what the third mile feels like.

When a plan is handed to you, ask who has actually done the thing and what they would warn you about. If you are planning for other people, walk one leg of it yourself.