Doing anything other than crashing-out of a cat-5 with severed-limbs and missing fingers, toes and eyes doesn't have anything to do with fitness, but rather bike-handling skill and mental strategy. aaron200 really needs to learn:
- confident bike-handling; being able to make the bike carve the exact line on the road when and where you want it. This will take care of the nervous downhill and racing attitude.
- smooth drafting; stay 6-10" behind someone while maintaining exact speed without touching the brakes. Knowing how to soft-pedal.
- shifting proactively; downshift before slowing down for the corners and before jumping & sprinting. Shifting up as you spin up the gears without skipping too many cogs in between.
- reading other riders; learn to pick out who the dangerous sketchy ones are and avoid them. Find the strong, smooth riders who can pull you around the entire race and help you stay near the front
- reading the pack, figuring out how the pack moves around the course. Where are the tight slow spots, on the left or right side? Where are the openings?
- reaction time, knowing when to let go of one wheel and hopping onto another before it's too late. Too many beginners fixate on the wheel ahead of them (instead of looking at that rider's hips and past him). They end up getting swarmed on both sides when the guy ahead fades and they find themselves at the back of the pack in the slinky. In the 5s, your race may be over as that yo-yo effect robs you of tremendous energy and strength and you may not be able to recover
- tactics and strategy - putting all the above together in a series of moves, like chess. There are things you can do in step-1, then step-2, then step-3 fashion that will get you certain results. Such as moving up in the pack by 5-10 spots without exerting any extra energy at all. Or how to get on the wheel of the guy that's going to win the race 2-turns before the finish., etc.
As mentioned, only way you're gonna learn these things is by doing it. Find a club and ride lots with tonnes of other people. Do practice-crits, many areas have them once or twice a week. Get dropped often on club-rides and practice-races and learn how to get better. Everyone gets dropped X-number of times in the beginning. The sooner you experience #1, 2, then 3 and so on, the faster you'll reach your goals.