I'm going to guess you're in your early 20's, and that whether or not you realize it you're feeling the external pressure to "do something with your life." You need to step back and realize that you can't simply become a successful, valued member of society overnight, and that focusing on the end result while ignoring the steps that lead you there may be overwhelming.

This may sound cliche, but it works: sit down with a pen and paper, and write down the things you enjoy doing in life. Once you have a list of things you're truly passionate about, consider which of those might make for a viable, enjoyable career. Work backwards from there.

Say you want to be a doctor; well, you'll need a degree from med school. Before that, you need to be accepted into med school and pass it. In order to pull that off you need to make it through 4 years of undergrad with a high enough GPA that you'll be accepted to said medical school. You need to pass all your freshman classes before you worry about what's coming up in your sophomore, junior, or senior years. In order to qualify for classes next semester, you need to do well on the pre-reqs this semester. Ultimately, all that matters is that one semester right in front of you. On an even smaller scale than that, all that really matters is that you get up, go to class, and study every day this week.

Once you've established what your ultimate long term goal is can start breaking it down into manageable sub goals. Create a (realistic) timeline for accomplishing each goal and post it someplace where you'll see it every day so that when you start becoming overwhelmed or filled with self doubt over your ability to achieve your long term goal you can give your brain a reality check.

It also helps to establish a proportional rewards for completing various goals. Start with small rewards for your immediate goals, and plan out larger rewards for the major accomplishments. For example, treat yourself to a nice meal (whether it's home cooked or at a restaurant) every Friday as a reward for getting to work/class on time all week. Buy a new video game as a reward for getting A's on all your mid terms. Plan a trip to Europe as a reward for getting your bachelor's degree, etc...

Lastly, to throw a wrench in everything I just said, don't be so tightly focused on your goals that you miss out on the new experiences and random possibilities that life throws your way. When I was in my 20's I imagined myself becoming a computer programmer, but I realized during my junior year that I didn't want to sit in a cubicle all day and stare at lines of code. I became very depressed and listless, and probably would have written a post almost identical to yours had Reddit existed at the time. I dropped out of college figuring that it didn't make sense to incur debt for something I didn't want, and decided to get a full time job to make ends meet while I figured out what I wanted to do with my life.

Through a series of seemingly unrelated (at the time) jobs I met various people who shaped who I would become, and I started discovering what my passions were. Fast forward ten years, and now I have an awesome career doing something I love, in a field I never would have guessed had you asked me at age 22. I get paid well, I live within walking distance of my office, and my opinions/knowledge are respected and sought out by people in my industry.

edit: spelling