The discipline to conclude is as important as the courage to begin.

Beginning gets all the attention because it requires courage and is easy to celebrate. Concluding requires something less romantic, the willingness to keep going through a phase with no reward in it. Both are necessary and only one of them is widely admired.

Count your unfinished projects. If the number is high, the missing capacity is not courage. Practise concluding on something small and notice that it uses a different muscle entirely.