Many books, blogs, articles were written about what skills / qualities an entrepreneur must have to be successful.
Must he/she be extrovert or introvert? Is discipline, drive and “you fill for yourself” essential for entrepreneur to be successful? I think nobody can say for sure.
I have met many successful entrepreneurs and they were all sorts of people with all sorts of skills and all kinds of qualities.

One of the things that I believe is fundamental and necessary for entrepreneurs to succeed (not necessarily for employees) is ability to “delay gratification”.

Delayed gratification basically means that you will sacrifice something today so you can gain more in the future. Or as Zig Ziglar says: “Do what you have to do today, so you can do what you want tomorrow”.

There was a study with small kids done at Stanford.
This became known as “Marshmallow test”.
It goes as follows. Kid is left in room with one marshmallow. Provided he/she would not eat it until researcher comes back, they would receive second marshmallow.
Essentially, if they were able to delay gratification (pleasure) they would get twice as much. Kids who were able to do that were much better off later in life measured by SAT scores, BM index, income etc.

Now why is this so important for entrepeneur? In building your own company there must be lots of work, time and energy put in and only then (and maybe not) you will get results (second marshmallow).
Delayed gratification will take you through hard times at the beginning, keeps you driven and motivated.

More details on this you can find at Wikipedia or watch video on You Tube – Marshmallow test