Hi Lynda
I go to the gym about 5 days a week. I usually do a 30 minute class. I find that easier as once you are in, you are there for the duration of the class. Just going round the gym machines, its too easy to skip things and leave earlier! when you first go to the gym you will ache afterwards, but after a few sessions, that diminishes significantly. I also try to walk or cycle (cycle paths only) most days.
I would go to the gym more often for longer if I didn't have to work, I love it.
Could you maybe break into a jog while you are out with your dog?
It never hurts to have a new thead ;-)
D.