The idea of disposable income is pretty simple. Once your living expenses such as food, bills, and rent have been paid for, what you have left is at your disposal to use as you please, usually for investments or purchases. The way we use that money is a very personal choice. However, a far more precious commodity in my opinion is our time, because its one thing that we can never get more of. All we can do is make that absolute best use of the time we are allotted in life.
However, if you look at the way you spend your time, you may find that there are parts of your day or week that can be considered “disposable time”. If the average person slept 8 hours per day, worked 8 hours per day, and then fulfilled other obligations like running errands, helping family or friends, preparing meals, and so on, it would leave them with about 4 hours of disposable time. Of course, you could very easily argue that cooking a meal or helping a friend/family member are enjoyable tasks that you would choose to do with your available time anyway. So what part of your day is truly disposable?
For me, it's the moments when you need to choose what to do in a given period and an opportunity cost presents itself. Does volunteering for an organization that you care about outweigh the fact that you would be spending less time with your family? How do you determine if you are spending your time wisely and for maximum benefit? I’m not saying that you need to analyze every leisure activity you do in order to determine its worth, but everyone can benefit from looking at the choices they make from a bird’s eye view. Think about the time your leisure activities will take, what time they will take away from other possible activities, as well as the long term benefits, not just the short term ones.