Learn to say "no" more frequently and more firmly. One of the easiest ways to create or enforce an interpersonal and physical boundary is to become more comfortable saying "no." Consistently saying "yes" instead when you'd rather not participate, have a conversation, or offer help gives your neighbor a different message about boundaries. Difficulty saying "no" can result from feeling obligated to put the feelings or needs of others before your own feelings or needs. This, explains the Mayo Clinic, can actually increase feelings of stress that can lead to chronic and preventable conditions such as anxiety and depression. Gradually increase your willingness to decline an invitation from your neighbor, and then identify and address barriers to your ability to enforce this kind of boundary.

Identify your boundaries proactively, not in reaction to your neighbor's behavior. Being proactive, for example, involves clearly stating to your neighbor in conversation that you are a light sleeper and go to bed relatively early. This approach, rather than calling your neighbor at 2 o'clock in the morning when his or her dog has been barking all night, gives your neighbor the opportunity to react in a way that doesn't feel defensive. Assure your neighbor that you will afford them the same considerations based on their needs.

Create identification markers for your physical boundaries. At times, neighbors may inadvertently cross property lines with their landscaping or outdoor items. Creating a solid identification line that defines your property can prevent problems caused by your neighbor using a portion of your yard as his or her own. After placing plants, garden ornaments, fencing or similar guides down, consider communicating to your neighbor that the markers are a means to define both sides of the property.

Increase communication with your neighbor. It's sometimes easy to simply avoid contact with a neighbor, particularly if he or she is encroaching on your boundaries. While this approach may help you avoid conflict, it isn't solving the problem and, in fact, it can create hostility between you and your neighbor. Wait for a moment when you and your neighbor aren't busy and when you aren't feeling angry or defensive. Sit down with your neighbor and frankly discuss what you are feeling, being specific about his or her behaviors without assuming what his or her intentions are. While the conversation may feel a bit uncomfortable for both of you, it can open lines of communication that can improve your relationship.