My mom got a treadmill for her birthday in March. She's been losing weight too. I don't know how much she's lost so far, but last time I asked she'd lost 17 lbs, IIRC.
I went to my parents' house 3 times in the last week to use the treadmill (days where the weather wasn't good enough to go for a good bike-ride). The first day I was hardly able to do 20 minutes. The second day, I did 22 minutes, and didn't feel like I was going to collapse. :-)
Last night I did over 36 minutes, and felt like I could have done 50, but I didn't want to push it. It's a good feeling.
I can feel how exercising has affected my daily activities -- going up and down stairs, bending over (hey when you have to lose 70 lbs, believe me, bending over to pick something up can be a challenge!), and walking around is much easier now. I still weigh the same, but I have way more energy.
This is a one year battle, I'm only 1/52nd of the way through it. Time to call the family doctor to arrange an appointment.