give it away
So I want to start by offering you a free no-tech life hack, and all it requires of you is this: that you change your posture for two minutes. But before I give it away, I want to ask you to right now do a little audit of your body and what you're doing with your body
What does "give it away" in line 2 mean?

Question

Answer

Just means the speaker has something to say, but before doing so (i.e. "give it away") the speaker wants you to do something first.

Think of "giving it away" as "to reveal/ expose something".

Answer

I agree with previous answer, but there is an interesting second idea here.  To give something away can also mean to hand it over free of charge.  Given that there is a reference to a free no-tech life hack on the first line, there is an interesting echo here of the possible second meaning.

But I think Darryl Wee's answer about reveal/expose is the primary meaning.