When I see pictures of California sea otters, floating lazily on their backs, eating sea urchins off their chest, they certainly look happy and relaxed.
https://www.esa.org/esa/wp-content/uploads/2014/08/sea-otter-with-urchins.jpg
I would hate to be reincarnated as a star-nosed mole:
A regular old domestic moggy (cat). If you're lucky, you'll be adopted by good humans and be pampered for life. If not, you have enough of the wild left in you to look after yourself pretty well in most circumstances.