You didn't mention your own experience with accountability. Do you practice what you preach?
I have had friends that at one time I did this with and then they lost interest. I also got paired up with a stranger, but somehow oddly we fell out of synch quickly. What has worked for me is a service that initially was a bonusl for a high-priced internet marketing course. I think most folks cancelled soon after the trial, but I kept going. I then stopped for a while, but i've restarted. I actually pay for the accountability buddy and because it's her job, she makes it happen and I get nudging and coaching. I thought a buddy system would work better, but what is working for me is paying someone for one-way accountability.