My experience with "bad" emotions: you can't really control them, all you can do is control how you react to them. Becoming comfortable with negative feelings is a valuable life skill that will always serve you well. So, accepting negative feelings (FOMO) and not fleeing from them (back into YouTube) is an important first step here.

Then, change the narrative. If you feel FOMO, channel it to:

• Reading a book
• Playing a game
• Watching TV
• Doing some kind of fun hobby

Gradually you will feel less FOMO and more interest in the activities you use to replace it. But it will suck and you will backslide. It's okay, it's a process.

Part of changing the narrative is also to engage in less structured activities that induce FOMO in you. Are your friends (or a specific friend) creating FOMO for you when you interact out with them? Do the feelings happen more when you engage with a specific social media platforms? Is there a time of day or a particular place that creates it more than others?

Changing your habits to avoid those triggers will gradually reduce your feelings as well.