I second all of the above. My DH was fairly ambivalent about the idea of natural birth until we watched The Business of Being Born, and after that he was absolutely convinced of reasons to go for the natural options. We also did an independent birth class.

I'd also recommend reading Gentle Birth, Gentle Mothering, which has some good, balanced information about all the interventions you might be faced with during labour and birth. Oh, and there's plenty of information on the BellyBelly website about this as well.

Unfortunately your chances of having a natural birth will be impacted by your DH - if he can't handle seeing you in pain, he's likely to consent to you having interventions (like an epidural, for example) when you are at your most vulnerable. You might like to consider hiring a Doula to support both you and your DH through the labour and birth - someone who can be objective and support your wishes regardless of your DH's emotive response to seeing you in pain. Doula, doula, doula - she got me through!

You NEED your DH to be behind you on this. His education is probably more important than yours when preparing for a natural birth!

Oh, and my DH sometimes questioned my capacity to handle the pain, and the marathon of natural birth. Just so you know, the only exercise I did during pregnancy was some low-key swimming (read: floating). I managed 21 hours of labour with only natural pain relief and gas to get me through - so I'm testament that you CAN birth naturally no matter how "fit" you are. Your body is equipped to birth naturally!

Good luck!