What about this 30 Day Shred thing that's very popular on here? Have only just ordered the DVD but apparently it's a tough 20-min a day work out.
As far as motivation goes, it's controversial I know but when I was losing 2.5 stones I weighed myself every day. It wasn't because I expected to see a daily loss but so that I was always conscious of where I was up to. Before that, if I'd eaten something 'bad' I used to just write the rest of the day off and hate myself for it. I did keep the weight off once I'd lost it until I got pregnant, by keeping a close eye on the scales.
Another thing that helped me was to give myself a day 'off' once a week, or once a fortnight when the weight loss slowed down. That way I didn't feel too deprived. It meant the loss was a bit slow, but I averaged about 1lb a week even with PCOS. I was using WeightWatchers points but not attending meetings.
I'm at it again now after having DD. having said that I'm still more than a stone lighter than I was originally (I was 12st 9lbs at 5'4" and currently 11st 6lbs).
Finally, I'm a greedy pig and thought I'd never do it. I was always starting a new weight loss regime. Something clicked though, and it helps that I kind of enjoy exercise. what I mean is, if I can do it, so can you, but you've got to be consistent.