For tough meat: Make hamburger with at least 10% fat, maybe more.
Cube it as mentioned earlier in thread (thanks pondweed). You can take steaks to butcher and they will run it through cubing machine too.
Use MSG (Accent). It works but there are many cooks who will not use it.
Cook meat rare to medium rare. Just to where the blood stops running. Or
Cook meat a long time maybe in preasure cookers. then shread it with your thumbs and make it into chili.
Just a few suggestions that have worked for me.
first of all that is a beauty. i've heard that cutting the meat once rigor mortis has set in can cause it to be tough. i don't know how true that is. also i would think that should only affect the meat that was cut.