I was like you and always wanted to fly, but it took me until I was 40 to actually do it. Do it while you are still young - it's much harder learning something as complex as flying when you are just that little bit older.
Yes, it gets expensive. People say that being a sailor is like standing in a cold shower ripping up hundred dollar notes, and flying sometimes feels like you are standing in front of a fan with your wallet open. But along the way you'll have a series of amazing firsts - first flying lesson, first landing, first solo etc - and they are incredible experiences that you will never ever forget.
Find yourself a good flying school and a flying instructor who you click with. Don't be afraid to try a few different instructors until you find the right one for you. Pay lesson-by-lesson in case you decide the flying thing is not for you (or the flying school goes bust).
With work and a busy life outside flying it's taken me two years to get where I am, but I am pretty close now to achieving my lifelong goal of a private pilots licence. It's the single best decision I ever made.