Patient presents with muscle deconditioning, characterized by reduced muscle strength, endurance, and power.  Symptoms include generalized weakness, easy fatigability, and difficulty performing activities of daily living (ADLs) such as walking, climbing stairs, or carrying groceries.  Onset is gradual, attributed to prolonged inactivity secondary to recent hospitalization for pneumonia.  Physical examination reveals decreased muscle mass in the bilateral lower extremities, reduced grip strength, and limited range of motion.  No evidence of muscle atrophy or neurological deficits.  Diagnosis of muscle deconditioning is supported by patient history, physical findings, and absence of alternative diagnoses such as myopathy or neuropathy.  Differential diagnoses considered included sarcopenia, disuse atrophy, and debility.  Plan includes physical therapy referral for a progressive exercise program focusing on strength training, aerobic conditioning, and functional mobility exercises.  Patient education provided regarding the importance of regular physical activity and a balanced diet to improve muscle function and prevent future deconditioning.  Follow-up scheduled in four weeks to assess progress and modify treatment plan as needed.  ICD-10 code R53.81 (Weakness) and CPT codes for evaluation and management (E/M) services, as well as physical therapy, will be used for billing purposes.  Prognosis is good with consistent adherence to the prescribed therapy regimen.