What Am I Riddles

Question: When you don't have enough of me, you feel a kind of gloom. But when you are using me, it is time that you consume. What am I?

Question: A man travels by wagon,
brings joy each evening,
but depression by the morning.

Who is he?

Question: We have what we did not find; what we did find we left behind.

[What do we have?]

Question: People are scared of me but I am loved by some. I can be your best friend but could become your enemy in a blink of an eye. What am I?

Question: Drop me and the world will shatter,
and you can always find me where you empty your bladder.

What am I?