If everything is "by choice", then what is the place of astrology? What is the place of Feng Shui?
What I can say is that we are influenced by Heaven and Earth to make a choice. Heaven also confines your choice with limitation. It is just like playing a computer game. You have to choose the weapons first. You are, however, unable to choose anything other than from the list of weapons available. If you play a different game, you will have a different list and the software will also provide you with different paths to walk on.
Among the three potentials (San Cai 三才), Heaven comes first. It affects the other two tremendously. In Chinese Astrology, the four pillars provide the fundamental ingredients to develop the character of a person. It is during the growth of a person that he builds up his character with these fundamental ingredients under the influence of Earth and Man (environment/education/friends). It is then the character of the person that guides him to make a choice when he walks the path of life.
The whole thing is an ongoing process. Nothing is written on the rocks. The picture, however, is to be painted with given instruments on given materials (paper/canvas). This is to say, not everyone is born with the same potential. One can only have the kind of achievement limited by the potential he is given at birth. Assessment of the potential is one part of astrology. It has a very important place. That is why Confucius said, "If you do not understand your destiny, you cannot be an honourable man 不知命無以為君子".
The term "honourable man" may not be a good translation of "Jun Zi 君子". The term actually refers to one who lives his life according to Heaven's will with the assumption that Heaven always means well. This is one of the more important core ideas of Confucianism.