I am 33 and still trying to figure out "what I want to be when I grow up." I too have a good job at a large company - decent salary, great benefits, but very, very high stress. I have been there eight years, and my DH is now there too working a job that he is way, way over qualified for, just so we can pay the bills. We are both miserable there and planning to make a change - may mean going back to school. My advice is...
1.) Evalulate your life. Are you happy? Does your job and the money you make there feed into your circle of values, whatever they may be (e.g. security, time with family, giving back).
2.) If you are not happy, decide what you need to be happy. Is it that your career doesn't fulfill you? Is it that the area you live in doesn't work for you and your family? Is it that the job you have currently is too stressful? Is it that you have a personal goal of earning that degree?
3.) Figure out what career/degree would suit you best - your personal gifts and talents, what you want out of life, the lifestyle you want for your family. Are you filfilling your purpose here on Earth?
It is not about money. If you are in debt now, obviouslly you need to make a plan to deal with that. You have to pay your bills and meet your obligations. But while you are doing that, figure out your next step. Please don't just look for a high paying career. That may make other areas of your life suffer.
If you are going to invest the time and money in going back to school, make it count. It's OK if you end up starting over in another field, if what you will be doing is gona make you happy, your family happier in turn, and help you give back to the world.
Society may tell you that a big house, big car, and lots of stuff is what you are striving for (i.e. you need lots of money), but that is just a big ole lie that traps so many into a lifestyle that is making them miserable and just plain killing them. So many are living paycheck to paycheck while the credit card companies make a fortune off their mistfortune and mistakes. Take it from someone who knows and is working hard to make a change.
Going back to school at any age is a smart move, if you do so to help fulfill your purpose in life and if you do it to make your life and the life of others better. I wish you all the luck in the world.