One afternoon I was attending a lecture by one of the very respectable old boy of our school. He told us about an incident that happened before India became independent. He told that Chacha Nehru had once said "Indians need to have a scientific temper". He explained that by scientific temper he meant the habit of asking why? The eagerness to know the very reason for the job one is performing.
Yes we have developed a lot since independence but the need for scientific temper still exists. Ask yourself why you are doing the job which you are doing that very moment. One of the biggest failures is doing perfectly something which need not be done at all. A teacher comes in the class and explains you a concept then you must have the eagerness to ask why I am being taught this. How is this topic going to help me? What is the practical approach behind it?
When you lie down on your bed at night think what all you did that day and why you did them. Did you really have a reason for what you did? Was your effort really worth it? Learn what you should have done and discover what you could have done. Implement it from the next day and within a week you'll start to feel the change. One should have within him the scientific temper. The temper to ask why..?