Yeah, go for a "fun" ride and tell yourself it can be as short as you feel like making it. Just get on and start going. If you only go down the street and back, at least you will have ridden your bike.

As for weight loss, what worked for me was The Weigh Down Diet, which basically teaches you how to listen to your body's hunger and fullness signals and eat "less food". No calorie counting, fat counting, or even any food restrictions. Just less of it. Another book of similar philosophy is Thin Within. I lost 60 lbs 11 years ago because of Weigh Down and kept it off.