Although I enjoy working out I dislike being in doors when the sun returns after Winter. Going for a walk in the Spring is such a great alternative way to keep fit, which everyone can enjoy.
It is recommended that you aim to walk 3-4 miles a day. Sounds like a lot more than you expect even if your days are spent running errands.
During a long day at a desk, having a change of scenery can boost brain power for the afternoon (avoiding the dreaded graveyard shift). If there is one near by then a walk into the woods can provide some added inspiration. This is as in the Spring since the bluebells come out!
If you find it hard to switch off during working hours but have a goal orientated mind then perhaps a pedometer could help. There are so many available at the shops and some even enable you to share and compete with your friends. In the Spring there are always so many flowers out such as Bluebells.
If you live and work in the City, why not try leaving a little earlier each morning. You could walk to and from the station each day to ensure you make up some steps early.
Work above the ground floor level? You could take the stairs instead of the lift. This would not only keep you moving but also avoid the people traffic at peak times.