Any possible reasons on why am i so pessimistic about a lot of things?

For about a year now, I started becoming really pessimistic about things for no reason. I'm currently a college student, and occasionally I would be motivated to look forward to graduation. However, there would be many days where I would feel like I'm just wasting time, money, and work thinking I probably will fail in the future and not find a career or anything or something bad is going to happen. Consequently, I take more cles and keep myself busy with work so that I won't have to think about anything other than work, but it's really tiring and when I'm not busy, thoughts of the future really frighten me. Any opinions, suggestions, or anything else would be nice. Thanks.