How can I charge my MacBook Pro at work?
The USB ports in the Desktop and monitors don't provide enough power to charge your MacBook. These ports tend to be build "to spec", meaning they output only about 500mA (USB 2.0) or 900mA (USB 3.0). Sometimes PCs have dedicated charging ports (maybe colored yellow) which provide more than 1A (they exceed the official USB specs), but that's still not nearly enough to charge a laptop. [1]

So you will need to get a charger (or a hub/dock[2]) that supports the "power delivery" (PD) protocol.

You can get them from anywhere between 18 and 100 Watts, and the power output makes a big difference in how fast your MacBook will charge. If you have patience, especially if you're not using the computer while it's charging, you can get away with a lower power (and smaller!) adapter (I use a 56W one, I would not recommend going lower than about 45W). Companies like Anker, Aukey, RavPower make some that are much cheaper and more compact than the original Apple charger.

[1]: The power delivery protocol allows the power supply to step up the voltage in order to provide more power at a reasonable current. The Apple 61W charger goes up to about 3A at 21V (the equivalent of 12.2A at 5V, or 24 times as much current as a USB 2.0 port can provide).

[2]: Note that some of the USB PD compatible hubs need a USB-C PD input in order to provide power on the output, so your best bet is to get a USB-C charger with Power Delivery and skip the hub. The ones that don't need a PD input tend to be (expensive) docks with lots of different ports.

Here are Apple's recommendations for how much power your charger should have: https://support.apple.com/en-us/HT201700