My elbow hurts!

Maybe your pain this morning is related to doing the tricep extenions. If your elbow hurts when doing tri extensions, lower the weight you're doing and check your form. You can probably get as good of a workout with lower weight and slower reps/more reps. Also, consider doing different tri exercises. I prefer to use the tri machine to do tri pushdowns, but if you're strong enough, it'd be about the same to do tri dips. If nothing else, you could at least not do that particular exercise as much.

Pay close attention to your form on your other upper body exercises. If you have trouble maintaining very good form at the weights you're using, lower the weight.

Also, see if extra stretching helps. Since I've begun taking the time to do a thorough stretch before running, my knees have hurt a lot less.

I hope your elbow feels better soon. Good luck.