I Feel Worthless

It feels like everyone else's life is moving forward, and doing great things while I'm stuck in place. I haven't been truly happy since I graduated from college, and I'm afraid I won't be happy again. It's been 4 years since graduating from college, and I haven't found a job in my field yet. Meanwhile, all my friends found where they belong. I am happy for them, although I have a hard time expressing it because I just feel so numb to life anymore. I seem to fail at everything I work towards, and everything I set out to do. What I'm afraid of is my friends all realizing they're better off without me, and leaving me behind because I peaked in college.