I add and drop weight regularly as my interests swing between weight lifting and cycling. At the moment I'm dropping weight to have a more competitive year on the bike.
I've dropped 10 lbs in 3 weeks, which is on target (I'm dropping ~25lbs).
I've swapped to a cooked breakfast, eat more for lunch and less for supper. I've cut out beer during the week. I don't each much bread or other processed foods. If it looks like a plant of chunk of animal I'll eat it, but that's it. My intake is the same or slightly higher than 'normal' but calories are focused in the first half of the day rather than the second which is my worst habit.
I train an hour every morning (Mon-Fri), 40 minutes bike, 20 minutes weights. Walk and hour a day (2 hours at weekends) and aim to get out on the mountainbike for 2 hours in the week at some point.
I expect another 10 lbs like this, the last 5 lbs will need require a drop in calories, or more exercise (which is less likely as I don't have the time).
Motivation is easy enough. Pick some races to enter. Set a target for each. It's the only reason I race.