Oh yeah SWIMMING!! Wow, what a clarity of mind that comes over me when I am underwater, how did I forget to mention this? There is simply no bad day that can follow me into the water.
Good food usually does it but appetite isn't always available when feeling extra down.
Good weed is a sure-shot for me if I haven't smoked already that day. The anxiolytic effects are extremely apparent and therapeutic on the first smoke of the day, especially if you're feeling particularly anxious or upset. Kratom/opiates aren't even that reliable in this sense. I've eaten handfuls of percocets and then felt worse in the past.
A lover, if available. If not, some good porn and a date with righty usually provides a decent mental shift.
Sleeping for SURE makes me move past a bad day or thoughts, but sleep isn't always easy. Actually, it rarely is.
A SMALL amount of whiskey/hard-A can be beneficial if you're in a really bad mental state, but I think we all know how that goes. That first shot provides a very effective release in stress, tension and anxiety and can move your mental state to a more positive realm, but then there is the completely inevitable "Well, just one more to keep the buzz going" which turns into "just another to top 'er off" which turns into "I need a double" which turns into "Well, I'm partying now, might as well do A, B and C". Lather rinse repeat.
A good cup of coffee at a calm, positive locally-owned coffee shop can lift one's spirits. A good conversation with a stranger at said coffee shop is the best!
If money isn't a big problem, treat yourself to something nice. A present, or fun activity, or uncommon indulgence to pamper one's self always feels good, especially if you're doing it in the name of well-being.
Walk through a dog park, even if you don't have a dog. If you don't smile at least once during that walk, you're dealing with a serious issue and should probably seek help. Seriously, who doesn't smile at the sight of dozens of happy frolicking pups?
I hope some of these help!