On the side of the shower opening that will support the door, hold a jamb piece against the wall so that its lower end fits into the base track. Without moving the track, use a 4-foot level to adjust the jamb until it's plumb. Stick a pencil through the jamb's screw holes to mark the wall.
I was asked to answer, so I'll give this my best shot, please know that I do not have any specialized or trained medical knowledge, only practical experience from Ashtanga yoga and meditation. So, yes, walking does reduce anxiety. 1.
Humans are told to get exercise to help relieve stress. It works for dogs too. Burning off some of that tension by going for a walk, a run, or playing in the yard or park is a great anxiety reliever for a dog. It will tire him out, perhaps enough to calm him down when he comes back inside after the exercise.