Hadith - The deen is easy

Abu Hurayra reported that the Prophet, may Allah bless him and grant him peace, said, "The deen is easy. Anyone who makes the deen too hard on himself will find it becomes too much for him. So aim for what is right, follow a middle path, accept the good news of the reward for right action, and seek help [to reach your goal by being constant in worshipping] in the morning, evening and some of the night."[al-Bukhari]

In one variant of al-Bukhari, "so aim for what is right, follow a middle path, and head for the goal in the morning, evening and some of the night and you will reach the goal." 

Riyad as-Salihin (The Meadows of the Righteous) of Iman Mohieddine Annawawi 631-676. Chapter 14:"On Moderation in Worship", Hadith No 145.