What drives you? How do you know you're on the right path to your goals? And if you decide that you're not, how can you get back on track?
Daniel Pink, author of five bestsellers, and a former speechwriter for Nobel Prize winner Al Gore, first tackled these big questions in his 2009 book Drive: The Surprising Truth About What Motivates Us.
Five years on, he's still campaigning for a change in the way people think about work.
Pink argues that traditional ways of motivating people don't work very well. The carrot and stick approach - offering people rewards if they do well, and punishing them if they don't - is out of date.
Instead he points to three more important factors.
"Do you have at least some control over what you do? Are you able to make progress to get better at something that matters? Do you know why you're doing something in the first place?" he asks.
In other words, a person must control what they are doing; they must have the chance to improve; and finally they must have a purpose.
"Answer those three questions and you'll be fine."
Of these three, the most important is purpose.
"Purpose is simply knowing why you're doing something, not only how to do it," says Pink.
"Sometimes purpose can be big and uplifting, say, addressing the climate crisis. Other times, it's just about making a contribution. When people [ask themselves why what they are doing matters], they perform better."
Having a purpose makes a difference, no matter what the task is. Pink points to a study of call centre workers raising money from university alumni. The callers were split into three groups, each given a different passage to read before starting.
"The first group spent five minutes reading a neutral passage," Pink says. "The second group spent five minutes reading letters from people who used to work at the call centre testifying to the personal benefit they received from having worked there.
"The third group read letters from people who were on the receiving end of the money that was raised - for instance, students who couldn't afford to study there on their own, but got scholarships funded by the money raised by this call centre.
"What happened? The third group - the purpose group - raised twice as much money and twice as many pledges as other groups. Five minutes of reading about the purpose of their job doubled their productivity."
That's why drive from within a person is more powerful than anything that comes from the outside.
But external factors are important, too. Safety, belonging and respect have to be in place before a worker or student can reach their potential. One example of respect is being treated fairly by your teachers.
To live happier lives, we need the freedom to make our own decisions, to improve our abilities and to work towards our lifelong goals.
Choosing the right kind of motivation makes things a whole lot easier. Pink offered five simple pieces of advice to make the most of your potential, whether at school, university or in the workplace.
"Don't over-plan. Things change quickly. Make decisions for the value of what you're doing now rather than what it might lead to," he says. "Focus more on using your strengths and less about repairing your weaknesses.
"Get over yourself. It's not about you.
"Remember that persistence trumps talent."
And finally, he says, "leave an imprint".