My flight instructor gave me two pieces of advice. 1.) Jet planes will kill you deader than dead. The little prop planes will just barely kill you. 2.) You start a flying career with a lot of luck and a little experience. You better hope that your experience catches up before your luck runs out.
Not sure if the first piece of advice helps much here, but there is something to be said about the second.
There are pros and cons to starting a PhD young and old. Personally, I lacked the maturity and experience to pursue a PhD in my 20s. At 32 I have the experience to approach a PhD like a job, which will suit me well. For those in their 20s, you have more luck than me,and probably more academic experience than I had at 20, so don't worry about it. Have fun and work hard.