Grade yourself like a strict teacher, then encourage yourself like a good coach.

Honest assessment and kindness are not opposites, they are two separate jobs. The strict part is about seeing the work exactly as it is, without rounding up. The encouraging part is about what happens next, because an accurate picture is useless if it leaves you too flat to use it. Most people manage one and skip the other.

Try doing both, in order, on one piece of work this week. First mark it honestly, with no excuses attached. Then write one line about your next move, in the voice you would use on a teammate who was trying.