Hazrat Abu Huraira says that as long as prayer keeps you engaged, you are in the state of prayer.

Hazrat Anas (may Allah be pleased with him) narrates that the Holy Prophet Muhammad (peace and blessings be upon him) once delayed the Isha prayer until midnight. Some people performed the prayer and started going to their homes. When the Holy Prophet (peace and blessings be upon him) arrived, a few people were still present in the mosque; he led them in prayer, and when he finished with salam, he turned his blessed face towards them and said, "People have performed the prayer and gone to sleep, but you have been in the state of prayer as long as you were waiting for it." Hazrat Anas (may Allah be pleased with him) says, "This scene is still before my eyes as if I can still see the shine of his blessed ring."