Honestly - and I'm not just saying this, because I don't have a huge pain threshold either - the belly ring didn't really hurt at all. The aftercare hurt more than the piercing. I was working a co-op job at the time - we had uniforms with high-waisted pants (yeah, that's hot!). I couldn't bend at the waist for about a week because the waistband of the pants put pressure on the ring.
Other than that, though, it really didn't hurt. I was surprised. I remember lying in the chair (dentist-style) and just cringing...then saying "are you going to do it already?!?!" and hearing "I already did". I looked down to see the needle in my stomach - he was just preparing to put the ring in. The look of it made me more woozy than the feel of it!