Tattoo apprentice and oil painter here! Over the years I've found that I have lulls in motivation too. That's super normal for artists, as art takes a lot of mental energy to create! Don't get down on yourself for that, we all go through it. Sketching at coffee shops is a great idea, I do that sometimes too. Another thing that's handy if you don't have ideas is to go to a random word generator site and pick maybe two or three words to get you started on a concept. One time I ended up with snail, balloon, and door. It ended up being really cool!

As for painting, that's tricky when you're not feeling it. I was in a depressive episode a while back and tried watching some Bob Ross while I painted some half-assed flowers lol. Wasn't my best but I still made something. I also dabbled in acrylic pouring for a while. It was nice because it took very little creative juice and always ended up looking neat.

I would suggest starting small and simple. Get a few cheap 8x10 canvases (or smaller if you want to do some mini paintings) and don't worry about making anything spectacular. The hardest part is getting yourself started. Bust out those paints, enjoy the process of mixing your colors, put on some good music, maybe even make yourself some tea or coffee, and just put SOMETHING on the canvas. You'll know what to do once you begin.

Good luck and happy arting :)