I second the idea about closure. Closure feels good. The problem is finding closure can take any time from hours to days for me. The "solution" is usually completely irrational.

I partially solved the problem by replacing the habit with physical exercise. Unfortunately light exercise won't do the trick, it has to be strenuous and last atleast for an hour.

Sometimes it seems I manage to simply suppress the habit, but maybe there are other replacement habits I'm not aware of.

I think that fits what I've read about worry.

From Chapter nine of "Resilience–How to Survive and Thrive in Any Situation A Teach Yourself Guide (Teach Yourself: Relationships & Self-Help) by Donald Robertson":

When we worry, we perceive danger, feel anxious, and naturally try to problem-solve in order to remove the perceived threat and achieve a sense of safety. As long as we believe future problems are threatening and remain unsolved there’s a tendency for our attention to automatically return to them as ‘unfinished business’, which partially explains why worry episodes tend to keep recurring.

[,,,]

Worry can therefore be seen as a failed attempt to avoid future dangers by mentally problem-solving and preparing to cope with them. Hence, people often feel reluctant to stop worrying because at some level they assume it helps to protect them against looming threats by giving them an opportunity to problem-solve and rehearse coping strategies, although it seldom does so very effectively and normally causes anxiety to escalate instead.

[...]

Rumination can be spotted and postponed in a similar way to worry