There is no definitive answer to this question as it depends on several factors, including your starting weight, your fitness level, and how much weight you want to lose. However, a general guideline is to aim for 30 minutes of walking per day, which can help you lose weight gradually and safely. If you are new to exercise, start with a shorter duration and gradually build up to 30 minutes over time. Remember to warm up and cool down before and after your walk, and to drink plenty of water to stay hydrated.