Shower Seat
Yes, I have two bad knees, a bad back, and several other health issues. Some years ago I had to stop taking tub baths, as I can't maneuver into sitting down in the tub, and if by some miracle I did manage it, I would not be able to get up again. I just kept taking showers, but my knees have gotten worse over the years, so several years ago I bought an in-tub bath chair. I am able to sit down for part of my shower. I still had a problem with the tub mat, as it wouldn't stay in place, and then I would have trouble getting up from the tub chair, as the tub floor is too slippery on it's own. I finally switched to taking a large towel, folding it in half, and then putting the back end of the folded towel under the front end of the bathtub chair, to hold the towel in place. This gives me enough traction on the tub floor and works better than the stupid tub mat ever did. The tub mat is too narrow to pin down under the bath tub chair legs, as I bought a wide tub chair, due to my weight. When my shower is over, the towel is too wet to hang over the side of the tub, so I leave the tub chair in the tub & drape the dripping towel over the chair to let it drain. The tub chair has little holes in it to drain water while using it anyway, so they also help in draining the towel. I have tried wringing the towel, but that doesn't get enough of the water out, so this is the best solution.
The tub chair does help me a lot when I need to rest while showering, and the towel pinned under the front legs of it really helps me with traction, so you should look into getting a tub chair. I got mine through Walmart's online store and had it delivered to my house. Now all I need to do is to figure out what to do with the bathtub mat that I no longer use.
_________________
If a man does not keep pace with his companions, perhaps it is because he hears a different drummer.
Let him step to the music which he hears, however measured, or far away.--Henry David Thoreau