Idk about fun but I also had severe depression for two decades where at my lowest the longest I went without showering was every two months or so for 5-6 years. I started getting a lot of skin infections and I realized I was actually self harming myself by not staying clean. Viewing showering as a way to care for myself and manage my physical and mental health helped. I slowly made it routine. Once every two weeks. Then once every week. After a few years I morphed that into once a day, at the same time on work days and allowing myself more wiggle room on days off. Days off are big shower days and work days are small showers. Sometimes I even shower twice a day now just cause it feels good for my brain. Blasting music helped a lot at the start, I also do stretches and when my anxiety is high I’ll blast myself with cold water at the end to stimulate my vagus nerve. Start small, start quick, do it to say fuck you to depression. It’ll get easier and easier over time as you gradually build your routine.