Question:
Assalamu Alaikum wa rahmatullahi wa Barakatuh
Thank you for your question.
In this matter, there is a difference between the obligatory and voluntary prayers. You may pray any voluntary prayer sitting down even if you have no issues however the reward would be lessened.
In regards to the obligatory prayers, it is not permissible to pray sitting down unless there is an absolute necessity. And that is the meaning of the prophetic hadith: “Pray while standing. If you cannot, then pray while seated
…” It is as Allah says: “Fear Allah as much as you can” (64:16). Necessity here means that a person cannot stand up or physically harms themselves by doing so. If it is a matter of discomfort or inconvenience, it would not qualify.Therefore, unless a doctor says otherwise in which case it becomes a necessity, you should continue to pray standing up for the obligatory prayers and seek the reward from Allah for the discomfort. As for your voluntary prayers, you may opt to sit down.
And Allah knows best.