Watching what I can't do

On one of my walks this afternoon at work to get to 10,000 steps a young guy ahead of me stops by a tree and and jumps up to grab the tree branch above his head and starts doing pullups.
Failure points for me;
1. I can't jump at all, not even an inch off the ground.
2. I can't reach my left arm above my shoulder.
3. I can't open my left hand to grab anything, when holding my left arm above my head to try to grab a bar to do a dead mans hang, can never get the fingers to open at the same time.
4. No ability to move the body off the dead mans hang at all.
But I did find a tree with a branch at shoulder height so I now can do this again:

Apple tree stroke rehab