According to a Hadith (sayings about the Prophet Muhammad p.b.u.h.) the original number of Salah (prayers) commanded by Allah was fifty a day. During his Night Journey to Jerusalem and the Heavens, the Prophet asked God to reduce the number several times, and so there are now five prayer times a day.
Many religious people feel that, although there are specific rules laid down for prayer, in a sense everything one does should be done 'prayerfully'. This way God, and the relationship with him, is never forgotten.