Do stretches, use moist heat, and keep moving. A shower would feel great. I had a terrible fall on the sidewalk about four years ago. My feet went right out from under me, which made me drop to my knees very hard on the pavement, and the velocity of the fall made me lunge forward and I stopped myself from hitting my head on the pavement by using my hands and wrists. I rolled over so I wouldn't land on my ostomy and hernia.
I was a little nervous for a few minutes because I have osteoporosis. Thank God I didn't break anything.
I got up, grabbed my dog's leash and continued with my walk. I hurt, was shaking inside, but also was thanking God I didn't break anything. You know, it was the best thing I could have done....keeping moving. I think if I sat down I would have been far stiffer. I was stiff for several days but each day got better and better. It did take six months for my knees to heal. They were punctured in many places from the pavement.
I hope you don't get as stiff as you might be anticipating. Keeping moving, going gentle stretching, and moist heat did the trick for me.
Sherrine