I once visited a health centre in California called Weimar in 2008.  They had a the slogan 'Walk, Walk, Walk' and I bought the T.Shirt!

They advocated walking 2-3 times a day, especially after meals and this will aid digestion.  It will also prevent you from sitting down which many do after eating.  Guilty as charged!  One doctor told us, 'walk fast as you can, as long as you can'.  He suggested while walking move your arms in motion with walking and you will build up a sweat and there will be no need to jog or run, in case you are unable to.  I also met a patient who arrived in a wheelchair some years ago and just from walking and going on a plant based diet who gained so much strength that he now walks several miles a day.   

So if you don't like gyms, can't do strenuous exercise, WALK, WALK WALK!