If I want something bad enough...can I get it ?

i know this is clechy ...but i need to know. Are somethings unreachable. i am not taking about being the next prez or something....I just want to get into a decent college of my liking...but i have to somehow raise my SAT score by 300-400 points....keep up my straight (A's) (for the first time) and p my lifegurading test. People tell me it is so hard to get in to universities.....and who ever said thinking about colleges is stressful was right.....I am trying so hard for the first time in my life I want something so bad...but its like throwing a dart at a target in the dark .....you just dont know. ANy good advice