After the sins of man, God gave man a life span of 3 scores and 10, which is 3*20+10=70. When you are 10 years and you are told you will leave for 70 years, you will most likely you have so much time, and 70 years wouldn't be here anytime son. When you are 60 and you look back on your life, you realise life has moved so fast, you would probably think you were just 10 years yesterday. You would probably be hoping to be 10 years old again. And that's if you would live to the 70 years.
Life is short. You would have a lot of time to be a coward when you are 60 but for now, why not take risks? It is said that at the end of life, you would regret things you've not done more than what you did. So obviously, you should have more things done than things undone. You will most likely have regrets, but wouldn't it be nice if your regrets are things that you made attempts at, instead of things you were too afraid to try.
What's holding you back. Have you completed a daunting task and found out that it wasn't that difficult to begin with? Have you ever finished with an exam and later gone through the paper and realised that it wasn't that difficult? The answers will probably be coming to you whiles going through and you wonder where the answers were when you were in the exam hall. Your fear was probably keeping your answers away. Fear of failing is even stopping you from starting.
When you want to take a risk, ask yourself what's the worst that can happen from your actions. Is it worth it? If it is, accept the worst possible outcome, own it and imagine living with it. Could you live with it when you imagined it? If you can, take the risk. You already waiting for whatever might happen, so I don't think you should be scared anymore. You already know what's coming and are willing to accept it so you can go all out.
In live, being cautious is the best way to stay safe and out of trouble, but it can't be always. You miss a lot when you only play on the safe side. Even in psychiatry, it's considered wrong when someone plays by the rules 100% of the time. You can't be always bottled up. Life is short, live a little. You can't always be getting in the pool by the stairs.