Reasons of constipation: Change in diet, lack of fluids, lack of exercise, may be a particular type of medication.  

Ways to get relief from constipation:  

1. Loosen up - Take one glass of warm water with half a spoon of lemon juice and a pinch of salt.
2. Ayurveda medicine - Add triphala powder to some warm water and have it in the night.        
3. Fibrous food - Food with high fiber content like spinach, broccoli etc is very helpful in improving digestive health.
4. Baking soda - Half cup of water with 1tea spoon of baking soda causes movement in the bowel and gives relief from constipation.