Barb, 45 minutes of PT IS vigorous exercise! I remember when I was in PT, after 45 minutes I came out of there some days just wanting to cry. Truth be told, sometimes I did.
yesterday was 4 miles walked before work, 2 miles at lunch and 2-1/2 hours at the gym on the weight machines. Still can't get past that 4 mile barrier, maybe next month 8)