Do you have something that looks like this? No? You should.
This meat mallet/tenderizer is my new favorite thing. I've used it plenty of times before, but I've recently discovered the difference it makes with chicken. If you use the flat side to pound the absolute hell out of a chicken breast before cooking it (whether baking, pan searing, whatever) it makes it SO TENDER AND SOFT.
Seriously, do it. Just spread your chicken between saran wrap and beat the hell out of it until it's the desired thickness for whatever you're making. You'll thank me later.