Isn't Islam fatalistic?

Muslims know that all things are from God and occur by His will. Thus, they tend to worry less about material matters and view the life of this world in proper perspective. A Muslim believer relies completely on God and knows that whatever happens is always for the best, whether he recognizes it or not, so he graciously accepts whatever cannot be changed. However, this does not mean that a Muslim sits around awaiting destiny and takes no positive action in life. On the contrary, Islam demands action and effort to change every undesirable situation, and this is a requirement of the faith. It totally rejects the teaching that one should not go to a doctor when ill but only pray to God for cure. If human beings had no ability to act, God could not justly expect them to do and not to do certain things. Far from being "fatalistic," Islam teaches that man's main obligation in life is to exert effort in obedience to God, which includes seeking benefit and avoiding harm. Islam teaches that human beings should take positive action in life and supplement it with prayer. Some people are lazy and careless and then blame the negative result on destiny or fate. Some even say that if God had willed, they would not have sinned or committed crimes. All this is entirely incorrect because He has provided complete guidance and instruction on how to live and has ordered upright conduct at all times. God has not ordered anything that man cannot do or prohibited anything he cannot avoid because His justice is complete and perfect. Each individual is held responsible within the limits of his own ability, but not beyond it.