Strava is a great motivator. I have some private segments setup so I can focus on topping myself. I also have quite a few public segments setup which many folks have ridden before - since these are some of my fav places to ride I do what I can to stay KOM. Also hunting for KOM's can make for some really fun intervals at places that I may not have known were good to ride. This fuels my competitive nature and has really helped me to progress (regardless of whether or not I get every KOM or even set a good time!). A problem here is sometimes its hard to just cool out on a recovery ride if fun segments are coming up.

But the greatest motivation is merely the joy of cycling, I'd still be out there solo pushin hard feelin the wind and adrenaline as events happen without any piece of electronics.