It depends what you want to work on. I just work on my arms strenght with weights before going to work. If you don't have weights just do pushups (that's what I wanted to do but still can't do a lot of them). I do the rest of the workout when I get home using an app, I don't know how it's called in english but translated is 'home workout'. Generally speaking you could do pushups, crunches, plank and squats.