Can somebody help me about joining the marines?

im 17 now. ok so i took my asvab test and scored a 81. im going to do my physical exam by the end of june 2010.i had asthma when i was like 7 when i lived in san francisco but then i moved and never had problems with it again. i mean i even ran a marathon last march. so my recruiter told me to lie when i get my physical. what should i do?And to join dep do i have to sign an open contract? i heard open contracts screw you over. how do i avoid open contracts. id like to get a job in intelligence. any help will be deeply appreciated.thanks