As others have mentioned, kneesovertoesguy, in particular sled pulls. I was having trouble squatting and bending down, and in the morning I had to go down the stairs backwards until my knees warmed up. I did sled pulls for one day and the next day I was able to walk down the stairs normally in the morning. I was also able to deep squat without massive warmups. I continued to do them 3x/week and saw drastic improvement. I haven't done them since I started another routine that isn't liked here, so I won't mention it.
Here's a sled I am considering for my back yard.
https://markbellslingshot.com/collec...s/stealth-sled