Hum, let's see. When exactly did your treatment end? Are you about a month out? I went back and checked my e-mails I sent for my husbands updates, and they note an increase in stamina at about 6-7 weeks out.
One of our member's husbands also went back to a very physical job - on the slopes of Alaska!!! - very early. She posts as KP5, and I think has responded to your thread. If you look at her early posts, I think you will find them inspiring and full of great advise. The following link is was one she wrote 7 weeks post TX - as you can see, there are ups and downs, but the long shifts in Alaska were managable for him.
7 Weeks Post TX for One Tough Dude