It can take A LOT of years of schooling to become a doctor (usually around 8 years of college) and then a few years of internship and residency. Becoming a nurse takes a lot less time (I think you can just get a bachelor's degree). But if you really want to be a doctor you should totally go for it because you can really help people and make a difference and it can be a very rewarding experience. Good luck with whatever you choose!
I have a few friends who are going through schooling to become a nurse and Im looking into it myself, it is hard work but if you work your hardest and study a lot you well be great. Anything that is a lot of work is the most rewarding.