If you've ever had the Sunday night shakes then you know the capital-relation well. Your time is soon to become someone else's, to do with as they please! And yet it can be scarier to contemplate life without this self-discipline that has been instilled in us since youth, that sustains our reputation as dependable employees, and informs our identity otherwise. People retire and die -- that sort of thing!
Not a penny of profit can come from a production system composed entirely of machines: this is part of what Marx is saying. So you've got to keep showing up -- you can't take half the year off to do something you'd like! Technology does its part, but the real trick behind capitalism is convincing human beings to work one portion of their lives as necessary for their own subsistence, and another portion as an unpaid contribution to their employer. The two parts come together in varying proportions and are expressed superficially as a working day, a working week, a working year, and so on.
Much of the politics of class conflict revolves around how the two components of a working day fit together, i.e. how much of the day is spent working for oneself and how much is given without compensation to an employer. At first employers made people work 18-hour days, etc., in order to maximize what they could get above and beyond the cost of subsistence for their workers.
Now employers use a number of different means, including lowering the cost of subsistence (e.g. making food and other commodities cheaper for the general population -- think of how fast food sustains the American family!); increasing productivity via technology; dividing compensation between more members of the household, as with women's emergence in the workforce; or increasing the number of hours in a workweek, as from a neat 40 in most of our parents' day to whatever unholy combination is fashionable now.
One of the contradictions here is that while human beings form the portion of capital out of which profit is made possible, technological advances in production throw increasing numbers of people out of work. This leads to a scenario which Marx called "the declining rate of profit" -- the profit-bearing portion of capital grows smaller in relation to its automated forms, which are in turn maximized for the productivity gains they support. This is one phenomenon which can contribute to a generalized crisis.
That's probably enough to think about for now. Just remember the importance of self-discipline in all things, with working for others at the top of your list!