It must be (adjective) (doing something)

Guess how other people feel using the phrase "It must be ___". For example:

It must be fun going on business trips all around the world like you do.

If you're talking about the past, you can say "It must have been ___":

It must have been hard raising three children on your own.

This expression is usually polite.

answer to (someone)

You "answer to" someone who's in charge of you, like your boss. This means that, if you make a mistake or do something you weren't supposed to, you will have to explain your mistake to this person.

Even if you own your own business, you still have to answer to investors and customers.

The idea of "answering to" someone is a little negative, so it's not the usual way to explain who your boss is. A more common phrase is "report to":

A: Who does Doug report to?

B: To Hyun Jung, I think.

If you think that you're completely independent and don't have to take orders from anyone, you can say this:

I answer to no one!