If you observe around yourself, nature tells you that God is the one who completes everything. God grows food from soil and fruits from trees. There are innumerable such phenomena which happen on a daily basis. The suns rises after the darkness of the night. 
While I was sitting outside, I realized that yesterday I had found on the internet that the sun would rise at 6.40 am. The sun set yesterday at 6.20 pm. The sun rises at a fixed time and sets at a fixed time, which you can know beforehand. This is so that you can regulate your time throughout your life. Just as you offer prayer at appointed times, you must discipline your life as well. 
The Quran says: إِنَّ الصَّلَاةَ كَانَتْ عَلَى الْمُؤْمِنِينَ كِتَابًا مَوْقُوتًا (4.103) Believers are under the obligation to say their prayers at the appointed hours.

This message is not only for prayer. It means your entire life should be time-bound. In God's nature, the sun rises at a fixed time and sets at a fixed time. You must make a programme for yourself according to the time you have.