Day 1:
Dumbbell chest press 3x12
Bowlex flyes 3x12
Tricep kick-backs 3x12
Dumbell overhead press 3x12
20 minute cardio
Day 2:
Dumbell lunges 3x12
Chair static hold 3xfailure
Dumbbell Romanian deadlifts 3x12
20minute jog
Day3
Dumbell rows 3x12
Lat pull down 3x12
Lower back extensions 3xwhatever
20 minutes cardio
Since you aren't trying to bulk up your routine doesn't matter that much. Your main goal is to just get all of your muscles active, so you can change this as long as you don't leave a muscle group out. I didn't list any bicep exercises because back exercises do a decent job of working biceps but you can always add those. Make sure you look up the proper form for each exercise before you do it.