I second what Roadraven said about warming up. I have figured ouyt tha I need about 25-30 minutes minimum to warm up (don't like to do hills before then), and I can really start to fly after about an hour (I'm 46). Dh doesn't seem to need any time to warm up and likes to hammer right away so this week, he gave me a 3 minute head start and I did about 10 k on the flats alone before we hit the hills. He hammers on the flats and catches me at the 25 minute mark. Works really well for us.

I also find the non-existant hills hard - partly because I hardly notice them visually and I end up trying to keep my pace up to what I was doing previously.

Good luck with whatever you end up doing - practice does help...