What it likes to be ambitious. According to me, it means that what you are doing right now is not enough for you and you want to achieve more and better things for yourself. But not everybody is ambitious, maybe when they are young, they become gung-ho about doing something really great but when they settle down in life, their ambitious goes down the drain or just plain vanishes and they work like a routine and normal person day in and day out. And then there are some people who have set their minds on doing something great or exciting during their early years and even after having set backs, they achieve their goals. I can say that they are risk takers and will do anything to achieve their goals. But most of the humans being even when acknowledging that they want to take risk are actually risk averse.
Look at how many people are enrolled in retirement plans without taking an active part in their investments. And how many people have a plan B when something happens to their job. It is easy to say that you are ambitious but it is the actual plan that you put into place to achieve your ambitiousness. You really have to accept your losses in order to achieve your goal but most of the people just shy away from that. It is the fear of failing that stops many people of achieving their goals and hence they become ambitious less for their entire lives.