I don't change mine.
I do it with timing belt, around 80k miles. Probably should be done earlier but it was not in bad shape when I replaced it.
Super easy to replace. Turn tensioner with wrench using the square nub sticking up (I use large crescent wrench for leverage). Remove belt. Replace belt. Done. You can pin the tensioner in place, rotated out of the way, but I don't bother.
Almost as easy as the bug: