I used to be tired and sad all the time as an adult. Then I had twin girls.

Now I'm too tired and too exhausted to be sad all the time.

I'm salaried, so yeah.

If you only eat fast food, stuff your face on snacks everyday, never have meaningful social interactions outside the internet, sleep very little, don't exercise and only work all day without a hobby or engaging entertainment. Yes, you'll eventually become sad and tired all the time.

Only when I eat chips all day and go to bed way too late

I don't even know anymore.