Hi welcome to HCm I have gone thru your query regarding rehab exercises which help one get fit after appendectomy . It is indeed a good sign that your son is back to eating well and on track for a full recovery . Dear , for your info , our body works well ,till it is not broken and repaired . A repaired part , always gives pains if you over exert , can t tolerate jerks of increased amount of intense exercise and other problems . As he has recovered , he should not worry at all . He will be able to achieve his goal gradually . Always start from warming up exercises and gradually increase stamina The strong immune system , which is helpful for our disease free total health , is incredibly complex because your body has many lines of defense to rid itself of foreign invaders. There is no better option than physical exercise. Brisk walking is the best exercise to begin with.Yoga -Pranayam - Deep Breathing , Kpalbhatti Rolling , Streching exercises not only help you gain strong muscles strong immune system and security from diseases but also gives you well shaped body Modification in your life style , food habits -include fiber,essential nutrients & antioxidants in natural form ,cheeze, milk , butter , veges ,fruit , with required work out , Yoga , pranayam deep breathing , are the piller of our strong immune system responsible for healthy disease free life . To give resistance from diseases & alley pains take a level spoon of turmeric powder with hot Milk + a spoon of almond oil , at bed time . Lemon juice with water , a pinch of salt and pepper before meals . Aloe vera juice + Amla . Ginger , garlic omega 3 - fish ,flax seeds ,coconut water , nuts all help strengthen the body and mind . It is suggested to consult your doctor for proper guidance if problem persist Hope this helps solves your query .Take care .All the best .Get well soon Don t hesitate to come back in case of any further query .