Honestly,that may be for the best...considering. If you were wearing just the boot you might still move your foot around and it would take longer to heal. The 3 weeks will go quickly. The situation sucks, but could be much worse. I wish you the best.
Yep, that was the reasoning for the cast, he didnt want me to move my foot, as the MRI showed fluid around the base of the tendon. He asked me if he casted my foot if I'd still ride horses, I told him I am taking up needle point. Lol