Generally speaking, the question reminded me of an anecdote that happened in one of the books I read (The Griffin / Der Greif by Hohlbein, apparently not available in English).

At one point the protagonist and a side character reach a heaven-like world and when they arrive everyone behaves weirdly and is not really doing anything and the character is super confused by that. Later, he asks the guy who brought him to his place: Why do people not do anything? Why do they not do mundane daily things or get up and fight against evil? (I don't remember it exactly, but that's approximately how it was!). And the answer was basically: Because they're immortal. There is no motivation for anything if you're immortal and live forever. Why do something if you have all the time of the world to do it. Every little piece of advantage in human history is because people are mortal and want to achieve progress before they die. If everyone would be immortal, there would be no progress anymore.

While reading it, it translated much better from the book than just my short summary, but that piece of literature blew my mind because it unveiled so many different facettes of immortality, motivation and progress which I never thought about like that. It's only like 2 or 3 pages in this 600 pages book, but that's the part I remember the most clear and vivid. And no, the rest of the book isn't bad!

Thanks for reminding me of this piece of literature, when I'm back home from work I will look for the book and browse these pages again to refresh the memory!

To answer this question on a more personal level, the thing that motivated me so far in live is my wish to see as much of the world as possible. After school I had the option to do a "lower class" vocational training and be content with a regular job or go study to make it possible for me to get "medium/higher class" jobs. And at that point I didn't have to think long to realize that I want to travel as much as possible in as many parts of the world as possible, and that was the main reason I picked the university and went ahead and studied. This, and probably the wish for a safe and easy-as-possible life without a lot of worries for my future family.