After having heavy meals in the morning or afternoon. Sit for a while, that too on the ground not on any chair or cushioned stuff. Sitting on the ground while having meals and after meals for 15-20 minutes greatly improves digestion process. If you are bored of sitting for that duration, prepare some paan() in the mean while sitting. This is will take 5-10 minutes of activity. Talk to your fellow's sitting nearby, and thus you will finish your 15-20 minutes of normal sitting activity after meals.
Some people do walking excercise after having meals, which is a bad practice. Once you finish meals, your digestive system needs strong gravity pull, which can only be provided by sitting but not doing walking excercise or having a brief walk.
Never sleep after having meals in the afternoon or night. Atleast give a gap of 30 mins, and then u can take a nap.