I used to always take my thoughts very seriously before I discovered meditation. One minute I'd have a thought that says "I'm so cool and attractive" and I'd take that thought seriously, then in another moment I'd have a though that says "I suck at everything and I'll never be happy" and I'd take that thought seriously. This led to me being depressed most of the time because the voice in my head was negative most of the time.

You see, when you identify with a thought in your head, that thought determines how you'll feel in that moment. For example, when you're worried about the future it's because you think something "bad" will happen, but in the moment when you are worried, nothing bad is actually happening. But since you've identified with a thought that says "It would be bad if such and such happened" you start to feel like it's actually happening .

The alternative to living life like this and being pushed around by your thoughts is to not to take them seriously. If I'm on the train and I see an attractive girl and my mind says "Oh she's so hot. I'd be so happy if she was my girlfriend", I just passively watch that thought like I'd watch clouds float by in the sky. If I believe that thought (which is taking it seriously) I'd start to feel unhappy because she isn't my girlfriend and then eventually I'd be trapped in a negative cycle of thoughts (I'm sure you know how the mind just snowballs with thoughts).

So don't take your thoughts seriously, realize that you are not your thoughts. When you do that, you'll no longer be worried or stressed about the future and you won't feel guilty about shit you did in the past. All that will be left for you is to be in the present, which is where life always is. This is the foundation of going your own way and a way to truly be care free.