Solitude is a door you close yourself. Isolation is one that closed on you. Only one is restful.

The difference is not how many hours you spend by yourself, it is who decided. Choosing quiet is restful because you can end it whenever you like, and knowing that is most of what makes it pleasant. When the choice was made for you, the same hours do something else entirely.

If the door was yours, enjoy it without defending it to anybody. If it closed from the other side, you have not failed at anything, and one small reach is usually enough to start: a message to one person, a club with low stakes, sitting somewhere different at lunch.