How do I start exercising when I'm out of shape?

Start small and build gradually. Begin with 20-30 minute walks three times a week, which is genuinely effective and won't destroy your motivation by being too hard. After two or three weeks, add light bodyweight exercises like squats, modified push-ups, and lunges. The key is consistency over intensity, so resist the urge to go all-out early on since that leads to soreness, injury, and quitting. Pick activities you actually enjoy, because that determines whether you stick with it. Set a specific schedule rather than saying "I'll exercise when I have time." Expect the first two weeks to feel awkward and tiring, but most people notice real improvement in energy and endurance within a month of consistent effort.