Think of what you can do, not what you can't. No-one is perfect, we all doubt ourselves, so take comfort in the fact even your most together-looking colleague/friend has doubts about herself. Confident people have insecurities, but don't let them prevent them from acting anyway. Only you can develop inner confidence, which is hard, but not impossible. Before any situation, ask"what's the worst that can happen?" We often catastrophise situations, making us live our lives in fear. In fact, the worst case scenario is very unlikely to happen, and no-one has ever died from embarrassment, failure or making a muppet of themselves. It happens to everyone at some point in their life!It's people who can grow from their mistakes, and take risks in themselves, who develop confidence. So go on, have a little faith in yourself, and give it a go -you may just surprise yourself!