How do I start exercising when completely out of shape?

Start with very low intensity and short duration. A 10-15 minute walk daily is a legitimate starting point, not a cop-out. The goal in the first few weeks is just building the habit and letting your body adapt, not burning calories or getting fit fast. Going too hard too soon leads to soreness, injury, and quitting. After a week or two, gradually add time or intensity. Walking can become brisk walking, then light jogging. Bodyweight exercises like modified push-ups, squats, and stretching work well at home with no equipment. Aim for consistency over intensity. Three to four sessions per week is plenty to start. Progress will feel slow at first but compounds quickly once your body adjusts.