Way back in the day (2001), the University of Maryland Student Body enacted the Student Honor Pledge.  It reads:

The Student Honor Pledge is the embodiment of the trust your professors place in you.  Maryland's faculty cares about its students, and it wants you to care, too.  Even if you don't sign the pledge, they still expect that you did good, honest work. They're never supposed to assume that you're cheating, and they don't randomly check assignments for dishonesty, without good reason. (If your professors do have reason suspect you are cheating, though, they are required to report it even if you signed the pledge.)

Technically, you aren't required to sign the pledge.  It's not supposed to feel like some meaningless task that you haaavvvee to do.  Instead, it's a choice you make as a student, which shows:  A) you know what it means to act honesty and B) you are choosing to do so.

Your professors want you to be inspired and use what you learn to have a great career.  But, if you don't sign the pledge, you aren't validating the huge amount of trust that your professors place in you, and they may ask you why you didn't.  Again, signing the pledge is supposed to be a choice, and if you don't sign the pledge, you're pretty much choosing to say, "I'm not sure what 'Academic Integrity' means, but it's not like I even care, anyway."

At the end of the day, you're going to be building relationships with your teachers that will both jump-start and last the rest of your career.  But, whatever relationship you have with one of your professors will be based on the trust built into the Pledge.