Should i?

i had this day highlighted on my calendar. the day where i apply and hopefully step foward in my scientic career. should i really go ahead with it? people are telling me to apply and see what happens. i can't do that. it's not a joke. it's something serious, something i have to be fully committed to for the next 4 years of my life. if i apply and i get it, there is no way i will give it up. there is no way to explain to anyone, who'd understand why i'd be giving it up. stay vs go. why can't the head and the heart ever agree? eventually this has to stop. i have to leave. there is no place for me here. as time passes, little by little my space will grow smaller. i dun want to be stuck doing a phd as it happens. leave while the memory is good, i was told. should i or shouldn't i?