What would you do if the place you lived in suffered a flood disaster? Would you climb to the top floor and wait to be saved, or would you climb floor by floor as the waters arose? While climbing to the roof, would you act slowly or try with all your might to reach the roof as soon as possible? Obviously, the wisest thing to do at such a moment would be to choose out of all the alternatives that would save you, the one which would yield the fastest result. Any other course would be quite out of the question. The person in this situation would be considered to have done his best by reaching the top floor  in the fastest manner possible. This is “choosing the best course.”
The believer makes use of all his material and spiritual means, every hour and even every second of his life in accordance with the will of Allah. In doing so, if he is required to make a choice among certain alternatives, he draws on his wisdom and listens to his conscience, thus behaving in a way which would please Allah. This means that he acts in compliance with Allah’s approval at the highest level.