For the past 15 years or so - in fits and starts - whatever exercise I've gotten aside from walking outdoors has come on a treadmill.
I'm on my second one now. My original analog-controlled Vitamaster ran (after a fashion) for 13 years and I left it behind in the basement in Georgetown when we moved to the Valley. Now I have a Horizon Fitness T62 - much smoother and more powerful with automatic incline adjustment and digital everything.
Aside from the machine itself, there is one indispensable accessory to keep me motivated and active - music to accompany the walk. The way I've played music has also changed dramatically since 1992 - and I daresay for the better. Here's a list of what I've used:
Stage 1 - FM radio on a "ghetto blaster".
This was my very first attempt and it was OK I suppose for a beginner. The advantage was quick and easy setup - just turn the radio on and dial up a classic rock station like Y95. Disadvantages were annoying though. I usually started my exercise section when the station had 10 minutes of commercials in between long sets of music. Then I'd usually get Pink Floyd's "Dark Side of the Moon" or something else that wasn't really up-tempo walk rock. Time to move on.
Stage 2 - Cassette tapes.
This was certainly better as I got to pick the music - no commercials either. Disadvantages were that I had to tape the music myself, make sure I started the tape at the beginning so I'd have 45 minutes of continuous rock to exercise to. Also the dam' tapes kept getting stretched by the awkward mechanism in the blaster, or small sections were erased without warning. I was soon looking for a better solution.
Stage 3 - CDs on a better ghetto blaster.
This was my preferred music source for many years. The advantages were that the music stayed clear and clean. I had a CD burner by then so I made my own CDs from my collection just as I had with tapes. No particular disadvantage other than I had a lot of CDs kicking around the basement.
Stage 4 - portable MP3 player.
I adopted this method when MP3 players shrank to the size of a cigarette lighter and I could stick one in my gym shorts. The advantage was size and portability. No big ghetto blaster any longer. However I hated ear buds and even with a good set of mini earphones the dangling cord kept getting in my way. Also I had a limited selection of songs - my player was only 128 MB. Add to that the fact that the battery would often die in the middle of a walk, and I needed another way. Fortunately I didn't have to go back to CDs.
Stage 5 - MP3s on a Linux computer.
Sarah's old Dell Dimension 4100 was perfect for this. I set it up in the basement near the treadmill, installed Ubuntu with Rhythmbox and 700 MP3s on it. Now it blasts away while I walk and never dies, seldom repeats and never gets in the way. The only disadvantage is maybe I now have too much choice - but hey, I can live with it. I think I've found my long term answer for walk rock.