question #3 Sahih Muslim 731b, Book 6, Hadith 135 : How can one incorporate flexibility in prayer while maintaining its essential components?

The Messenger of Allah (ﷺ) used to pray while sitting (when he grew old) and he recited in this position and when the recitation equal to thirty or forty verses was left, he would then stand up and recite (for this duration) in a standing position and then bowed himself and then prostrated himself and did the same in the second rak’ah.