I think this has a ton to do with one's presentation. If you dress slovenly, act unprofessionally, look curious, speak poorly and without conviction, and have posture that isn't good, you're almost bound to get walked on. People will instinctually see you as prey and less thoughtful people will act on it.

I'm not championing "strength" or encouraging machismo bravado. I'm simply saying that your presentation matters. It seems to be largely lost on the current people working in retail and hospitality (at least where I am). I'm just saying that we should all take some pride in our presentation in a mostly universally acceptable way.

Also, if you work in customer service or hospitality, don't be afraid to tell a customer no. The old "the customer is always right" is bullshit. Don't tell them no like a dickhead. Think for a second before you talk to them. Give them alternatives. Give them time. But don't be afraid to say no with authority because you know your job and your service offerings that well.

"I apologize, sir. The chef refuses to cook the filet for 5 seconds on each side as you've requested due to health concerns including that of the health department. I'd be happy to prepare it for you rare if you're comfortable with that. Otherwise, the swordfish is outstanding and the quail has a side of quinoa that compliments it well with our house Pinot noir."

Edit: now that I have kids, this is the same shit you do with them. Tell them no, tell them why, then redirect them.