I think I might be slipping into depression. How to prevent it?

The unfortunate news here is that... You can't. Everyone is on their own journey and you can fight, struggle, do 10000 different things to put a bandaid on a festering wound and it will just slow the healing. Even therapy can be not effective. Radical acceptance is the way. Accept your feelings, don't try to run away from them - you will be wasting years. While acceptance deals with the discomfort much faster and letting yourself feel bad is part of life. It's a natural feeling. The question here is to ask "what is it telling me and what should I change about my lifestyle to experience it less". But it wont go away completely, it's a part of our behaviour that's purpose is to show us that changes in our life are necessary to be made.

That's called ruminating. I do the same thing.
My only solution has been to distract myself. Sometimes it works, sometimes it doesn't.

Find a hobby, do something you like, try something new, join a club, exercise, craft, read a book, whatever you can to distract yourself in the moment.

@Miklee02 you need Jesus

Therapy can be a huge help if you can afford it. Otherwise, maybe try doing things you enjoy with or without people. Make a list of things you are grateful for. And try mindfulness meditation. You can Google what mindfulness is. When tough memory’s come up, you can use a grounding exercise, such as naming 5 things you can see, 4 things you can touch, 3 things you can hear, and 2 things you can smell. And if possible one thing you can taste. To ground you in the present moment

If you ever have a hard time try to
1. distract urself with something you like to do
2. let all the emotions out all in once, I used to have this pillow and i would just discard it little by little if i was mad or sad and it helped me preventing myself from sh. Hope it could help someone else someday.
3. Talk to one of us (or someone irl) if needed. Talking anonymously online may be the best start

What helped me was to try to live life like depression doesnt exist. I never wanted to go anywhere and locked myself in my room for days. But when I forced myself to do something with my life it helped me a little : )

Just have to fight the negative thoughts