Ask yourself one question: Why am I living the life I am?
This question has many simple answers, but is almost impossible to answer conclusively. Sure, you go to work everyday because you need money. Sure, you are a student because you want a better opportunity for success, or you find the subject matter interesting. Sure, you're poor because you can't get a better job. Whatever it may be, there is a reason, but most of the reasons come accross as excuses and do not address the cause of the situation. Even if you're situation is great, it is not likely that it occurred as a simple matter of choice. There are many many events that combined to bring the world to the state of being that it is in today, including your personal situation. And while choice alone did not bring youto your current situation, the next question you're going ask yourself is: What is the next action I'm going to take to live the life I want?
While you cannot control your situation entirely through choice, you can influence your direction by actively exercising your choice instead of floating where circumstance takes you. The tides still ebb and flow, and you are subjected to them, but you can make the choice to live a better life. The next thing you do after reading this should be an action to improve your life, no matter how small. It could be the choice to stretch out and touch your toes for the first time in 10 years. It could be to tell your spouse that you love him or her and you're willing to make things better. It could be to learn something new or teach somebody a skill. whatever your current situation is, you can make your next choice be one that improves your life. Act according to your choice now and stop drifting.