Walking will get you fit and you may even loose weight. If you do not have time to work out at the gym or for an hour, try walking a few times a day/week in 10 minute increments. You can add walking to your every day tasks without making time for it. When you go to work or the store, park farther away from the entrance. This can easily add 5-10 minutes of walking to an activity you already planned for.
At the end of the work day, try walking for 10-30 minutes. Walking will help relax you and releive some of the stress the work day may have brought.