Why To Not Not Start A Startup ~ Must Read!!!

Too Young
Too inexperienced
Not determined enough
Not smart enough
Know nothing about business
No cofounder
No idea
No room for more startups
Family to support
Independently wealthy
Not ready for commitment
Need for structure
Fear of uncertainty
Don't realize what you're avoiding
Parents want you to be a doctor
A job is the default

Source: http://www.paulgraham.com/notnot.html