Causes of tolerable harm not prohibited
16-1-2017 | IslamWeb
Question:
Assalamu alaykum Islamweb. I suffer from body imbalance. My right leg is somewhat shorter than my left leg. Due to this imbalance, I get muscular trigger points on my right side of my abdomen, which gives me pain, but the pain is bearable despite being very active. Whenever I engage in any activity, my right side is dominant. This has been happening for quite some time, and I do not think that the problem will ever go away since the soles of my feet are uneven. I suffer from Waswaas (devilish whisperings) and I overanalyze everything and that makes things difficult. I heard about the hadith that says that there should be neither harming nor reciprocating harm. My question is: can I continue being active through activities such as weightlifting and cycling even though I will get pain? By Allaah, the pain is something that I can tolerate, and it does not hurt all day long. Moreover, I am training smartly. So is it permissible to still train with the weights? Does the hadith apply in my situation? Thank you.
Answer:
All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallahu ‘alayhi wa sallam, is His slave and Messenger.
There is no blame on you in engaging in any activity of your choice that you can tolerate without incurring significant harm on yourself. As for what causes real harm, it must be avoided in application of the hadeeth that says, “There should be neither harming nor reciprocating harm.” [Maalik]
The scholars underlined that the harm that must be avoided is the significant harm that is beyond the person's ability to tolerate. Hence, we do not see any blame on you in engaging in the activities that you mentioned as long as the pain is tolerable, as you stated in the question.
Al-Bujayrimi 
wrote, “Regarding the statement: ‘what harms the body or mind is prohibited’ .... Al-Athra‘i said, ‘What is meant is the evident harm that is normally intolerable, not harm in general.’” [Tuhfat Al-Habeeb ‘ala Sharh Al-Khateeb]
We advise you to consult some doctors in this regard.
Allah knows best.