I have constipation. Is it due to the fact that I have a "lazy bowel"?

No. Constipation can be caused by many factors, the most common is a slow transit. The chronic use of laxatives can magnify the problem with slower transit and this is sometimes refered to as a 'lazy colon.'.
Lazy bowel is not . Really a medical diagnosis but there are several diseases which can slow the motility of your large bowel. You need a detailed examination including xrays, lab work and colonoscopy to further assess your constipation. Treatment is dependant on the etilogy but in general drink a lot of fluids, stay active and take atool softeners. Please see a GI doc if symptoms dont resolve.