[Michael Romanos]

I don't know where you picked up the idea that a young puppy should be made to tire. I would not exercise a four-six month old Corgi pup to the extent that you have. I would exercise an 18 month old- plus Corgi for anything up to 90 minutes daily and even longer once a week. But not any sooner. At four-five months my Pem Taylor would have stopped and crouched down and refuse to walk any further after 20 minutes - and I would carry him the rest of the way home.
However, if you break your 45 minutes a day into four walks of 10 minutes each, that would be great until he is over 6 months then say 3 walks of 15 minutes for 6-9 months.