Eagle Pose

Seriously, don't even worry about the leg part at the link. Just do the arms.

I also use these therapy balls: https://www.tuneupfitness.com/shop/massage-balls/therapy-ball-plus Keep them in the bag, and they go on either side of your spine and you roll up and down. But you can also take them out and use them individually in tons of ways. And they're great to travel with since they're small.