Lost 50lbs on the diet, now I'm doing a Century Ride

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I lost over 50 lbs in the last year using diet and moderate exercise. I started cycling (again) and although I have never been super into it before, I am enjoying the sport. I bought a new bike in the fall (I live in Michigan, so I have only been on it three or four times since November). I have decided to train for a century ride or two this summer (100 miles, maybe starting with a metric century of 100 km in late spring). Anybody have any training tips for me? Inspiration? Anybody willing to verbally kick my butt and keep me motivated?