HIGH STRESS!!! I would go home with headaches that wouldn't go away until late at night, sleep, and start over again. My weekends generally involved a after hours cell phone that truckers would call and yell at me at any point of the weekend. Seriously... I got a phone call at 2 am from a guy who just needed someone to yell at.
Negotiating is fun, and I got really good at it, but if you don't get the guy down low enough, or the load won't cover no matter how many phone calls you make, managers will let you know how unhappy they are.
As a capacity manager, the base pay is 32k plus monthly commission. The commission is there just as long as you land yourself on the right team. This is all PURE LUCK. I was on a team that was taking losses left and right (thankfully, that doesn't come out of your paycheck because it's not technically your fault) because their customer wasn't paying enough to make a profit moving the loads. On the other hand, I was on a different team that I was making $1-2,000 profit. But that's not because I negotiated better, it's just because the customer paid that account manager more money to move those particular loads.
If you can handle the high stress, high pressure, sales/negotiation driven work day in and day out (working over 40 hours as needed, weekends, and an after hours cell phone) for the base pay and no overtime, then awesome. Don't let me stop you....... but don't say I didn't warn you, either.