I walk every day. It is easy, can be done anywhere and doesn't require any special equipment. PLus it was a good place to start when I was heavier. Live by a river and enjoy mother nature every day as I walk .
Walking is absolutely the best, especially in the beginning. While I love doing weights, I start everyday with Cardio. When my watch vibrates to tell me to get active, I walk a couple blocks around the building where I work.