Two goals.

1) Lose Weight
2) Get fitter.

Goal one I've been accomplishing without Cycling but Cycling is making it even easier by not just restricting intake, but increase calorie expenditure.

Two is perhaps subjective and hard to quantify. But I really enjoy riding my bike. And I go faster and further as I progress, and I want to keep up with that.

I use the trainer indoors when I can't comfortably ride outdoors. I don't necessarily train for anything specific but I also don't train without a plan. I tend to follow TrainerRoads Aerobic Base plans right now.