Complex sentence: At the age of thirteen, he asserts that he won the National India Yoga Championship and was undefeated for the following three years and retired as the undisputed All-India National Yoga Champion.
Split into simpler sentences: At the age of thirteen, he claims to have won the National India Yoga Championship. He claims he was undefeated for the following three years and retired as the undisputed All-India National Yoga Champion.