Any help/recommendations?

Hello,

my concern is that my stero components (and digital cable box and Xbox) that are housed in my cabinet (closed in...not open shelf) is making it too hot in there. I haven't noticed any problems, sans the occasional 1-2 second blip from my DVR digital cable box. But, you can feel the heat (warm air) inside the cabinet.

My cabinet has a glass front door, and both I and my wife would like to keep it, if possible. It helps keep the dust out, and makes it look nicer than taking it off.

What I am considering doing is cutting a couple holes in the backing (like a tough cardboard...almost wood) for a couple 120mm fans and hooking those up to .....something. I say something, because I don't have a computer in the local vicinity, and I have no idea how I would go about hooking up a couple of 120mm fans to any sort of power supply?

Any help/recommendations?
Please help.

I didn't find the right solution from the internet.

References:
https://arstechnica.com/civis/viewtopic.php?f=6&t=421725
Talent Acquisition Video

Thank you.