A 58-year-old male from rural Maharashtra presents to a primary health centre with chest discomfort for 2 days. He is a farmer with no formal education, works 10–12 hours daily in fields, and has never had his blood pressure checked. On examination: BP 168/104 mmHg, HR 92/min, RR 18/min. He denies smoking and alcohol use. His father died of a 'heart attack' at age 62. Fasting blood glucose is 126 mg/dL, total cholesterol 248 mg/dL. What is the single most important modifiable risk factor for primary prevention of cardiovascular disease in this patient's demographic group in India?