Fear is a result of your relative comfort. It's one of the reasons why heuristic psychology is such a problem in the back country (e.g. I've ridden this line 1,000 times and never had an avalanche so my brain takes mental shortcuts that might ignore signs telling me that today is a day I could set one off). It's also one of the reasons why "easy styling" is a part of the process to work people into park riding. You start small on features you can reasonably handle, work up your comfort level on them, and then progressively get larger.
Everyone is different, and the level of self-preservation we feel will be different from those around us. Typically speaking, young men are less risk averse than young women or older adults. Although I don't think you need to focus on that as a reason for why you are having trouble. My guess is your injury has kicked up your preservation a notch. The best approach, would be to leave your friends to do their thing and get a coach/lesson so that you can focus on what you're doing instead of on what other people are doing.
It isn't a race to get to the top or to see how fast you can master something. You need to change your mindset to focusing on what you can accomplish and in a time frame that makes it happen safely. Sure, it can be frustrating if you feel like you are falling behind, but that rush to catch up is also probably leading to mistakes. It is much better to focus on technique (as has already been suggested), so that you have a strong foundation to build upon. Once you've done that, you'll exponentially get better and may even find that you're surpassing your friends who are "faster" at this point. Any idiot can go hit a box, but that doesn't make them good.
Last edited by Treegreen; 02-11-2013 at 08:16 PM.