There are a few exercises that you can do by the way: In the office talking on the phone, in the bus or even while tooth brushing. Today I balled my fist while eating my cornflakes.
As I’m a right-hander I first balled consciously my left fist and held it pressed. And then relaxes. I took the spoon with the left hand and continued eating my flakes and balled a fist with the right hand. After a few repetitions and while having breakfast I had done a work-out not only for my fingers and forearms, but I even -as they say- relieved a bit of stress.
Of course the breakfast lasted a bit longer this way, but at one go I even increased the coordination of my left hand.