When should I take rest days?

I have been going to the gym for a little less than a month now. Generally one day i will do legs (abductor, adductor, torso rotation, butt machine, calf extension, leg extension, leg curl, leg press) and the next i will do upper body (pullups, chinups, bench and shoulder press, row, tricep pulldown, and various other dumbbell activities i don't know the names of ). I do 3 sets of 5 for each and i never do the same one two days in a row but i was wondering if i should have some rest days where i don't do any? Should i just kinda go by what my body feels or should i have days where i don't lift even if i feel fine? I work a manual labor job so i am pretty careful about not overdoing it and hurting myself (particularly on upper body since my job requires lots of shoulder activity). I realize i should probably be getting some yoga or core/stretching type stuff in there as well. I'm 5'10.5" 135 lbs so i'm really not looking to do any cardio (definitely nothing with any impact i work on my feet all day so i won't) other than i suppose to get my heart rate up. Any suggestions would be much appreciated thank you.