Swimming is, indeed, excellent exercise when you have the time to visit a pool - and put in the lengths.
But what fits better into an everyday working life is the highly recommended 10,000 steps a day regime.
This can be part of normal day - and include walking to/from the station, a lunchtime stroll and/or a walk in the park.
About 2,000/3,500 calories are burned with this exercise, every week - which has a beneficial affect on almost every part of your body.
In this era of screen watching - often an integral past of work AND leisure - exercise is key; ideally outdoors in the fresh air.
Sports participation adds a social and competitive aspect to exercise - eliminating potential boredom.