Actions of worship depends on the heart, not the physical ability

The strength required to perform acts of obedience to Allaah never depends on physical ability, for there is no relation between obedience and physical ability or weakness. Thus, you would find a young man of 30 years old being prepared to lift 200 kilograms and run with it; however, if he stands behind the imaam for prayer whose recitation does not exceed 10 aayahs, you will find the man shifting between leaning on one foot and the other. Hence, there is no connection between physical ability and that of long acts of worship. Indeed, the connection of these acts of worship is to a sound heart. It is the heart that incites the body. There are examples for this. These include an old man who uses a walking stick and has passed 100 years old, praying nite prayer behind an imaam who recites a part of the Qur’aan in each unit of prayer. One day, the imaam reduced the length of the last part of the prayer because he heard the first call to prayer, and this means that the night prayer at the mosque has ended. When this happened, and the imaam performed the end of the prayer, the old man admonished the imaam saying, ‘Now the necessary time…,’ meaning what was most important time, the last third of the night, ‘… you shortened the length?’ On the contrary, there was old man who was more than 80 years old who prayed sitting for 10 or more years. One day, at a day of celebration, and it was time for the traditional of dance, he got up to dance with sword in hand. All of this is confirms Allaah ’s Words,

{إِنَّ سَعْيَكُمْ لَشَتَّىٰ}
Indeed, your efforts are diverse.” (AL-Layl 4)