It could take less than five minutes. Here's a step-by-step guide:
Get off of the couch.
Make sure you're dressed.
Open the door.
Walk next door (right or left - it doesn't matter).
Ring doorbell (or knock).
When door opens, introduce yourself and use customary greeting of the country in which you live.
Begin conversation.
Find common points of interest.
Use traditional conversational conclusion.
Walk back to your house.
Meeting your neighbor enhances the feel of community, deters crime, and heightens a sense of ownership. In other words, being a better neighbor makes for a better neighborhood.