I don't wish to be over critical here- its easy to be. I have a friend in a very similar position. You just have to get flying!!! Work in your local flying club, wash planes, take in the atmosphere- meet people who are retired airline pilots, test pilots and have been there and done that! As the previous post says tow gliders, save alittle money, fund a FI rating. None of these things will allow you to sit in the RHS of an airliner, HOWEVER you will meet people, and one thing leads on to the next. You might just be in the right place at the right time when that Falcon co-pilot suddenly leaves or when the small turbo prop regional airline or air taxi company on the airfield needs a new co-pilot.
Instead to many people want to go straight from flying school to flying a B737 on 45K a year. A facet of modern society I believe.
I realise its easy to give advice my friend. Best of luck!