There are times when we don't try new things because we are afraid. We fear the unknown. We may also fear failure. I never used to think I struggled with this but I've realized this past year how much I do. I put off getting my commercial driver's license for years -- for one I didn't have the "want to" and secondly, I was afraid of failure. After lots of stress, anxiety, and tons of study, VOILA! I passed the test!
Now I am at another crossroads where my want to and my need to don't exactly line up. I am taking Advanced Statistics (and I've NEVER EVER had a statistics class in the past). The first couple of days I was in a sort of fog where people were all speaking around me, but I didn't know the language. The old fear of failure began to creep in again. Yesterday was a turning point for me. All of a sudden, things started clicking and light bulbs started coming on. There is still a lot for me to learn, but I know with hard work and discipline, I can do just that -- learn. Whether I pass or fail isn't the end all (of course it could be the end of my PhD journey), but the real question is what have I learned from the experience.
So, I say all that to say, "Don't put it off anymore. Take a leap and try something new!"