“The brick walls are there for a reason. The brick walls are not there to keep us out; the brick walls are there to give us a chance to show how badly we want something. The brick walls are there to stop the people who don’t want it badly enough. They are there to stop the other people!” – Randy Pausch
Seriously, if you always put limits on what you can do, physical or anything else, it’ll spread over into the rest of your life. It’ll spread into your work, into your morality, into your entire being. There are no limits. There are plateaus, but you must not stay there, you must go beyond them. If it kills you, it kills you. A man must constantly exceed his level.
Security is mostly a superstition. It does not exist in nature. Avoiding danger is no safer in the long run than outright exposure. Life is either a daring adventure, or nothing.