A man came to the Prophet (saw) and said: O Messenger of Allah, teach me but make it concise. He said: When you stand to pray, pray like a man bidding farewell. Do not say anything for which you will have to apologize. And give up hope for what other people have. Narrated by Abu Ayyub al-Ansari
Make your prayer count when you stand to pray as if you'll not pray again. Hadith from ibn Majah book of Zuhd.