By thinking of your time away from work as "free time", or the time of freedom, you are creating a dichotomy in which your time at work is "slave time", or the time of servitude. But why would you want to spend a third of your life in servitude if you don't have to?
Well, you say, I have to work. But do you have to work as a slave? If that's how your job seems, then spend your "free time" trying to find a place or a type of work that allows you to do what you do during "free time." That way, all your time is free time, and you can live your life as a whole, instead of in two conflicting parts.