From my own experience, I have always avoided going out for the sole purpose of exercising. It was never fun for me. Then I got a job as a dog-walker and I was doing a large amount of walking and jogging very regularly. I hated it for quite a long time, and still am not enamored of the idea, but I got used to it and at times I still find a random urge to go out and run for long periods. I now find it a good way to organize my thoughts and escape my reality for a while, but if those reasons are absent, I feel no pull to do it.
I found: a) walking with a dog (or another person) makes it much more enjoyable, just to have the companionship and feel like you're not doing it alone. I think the "being alone for long periods" factor has always been one of my major excuses for avoiding exercise. And b) Podcasts. Find some good, long, enjoyable podcasts to listen to.
Wait Wait Don't Tell Me
was my favorite, and at a perfect length (~45 minutes), though I also enjoyed The News From Lake Wobegon
and Mugglecast
.