Please choose the correct ending to complete the given sentence: Pets and Animals: [header] How to make your labrador retriever happier [title] Walk your lab often. [step] Labs are very active dogs, especially in the first few years of their lives. They will have a lot of energy to spare every day, so a few long walks will become part of your daily routine.

Ending1: They'll also get a lot of exercise. So, when you are planning your walk, don't start with regular walks, since they'll get along much better with shorter walks. Ending2: [substeps] Plus, dogs are accustomed to their natural clock to know to be up at the most obvious hours. Whenever your pup gets up, they will immediately begin to trust the sound and environment, knowing that any unusual noises or movement that your labs may hear will be his cue to go. Ending3: This will not only help exercise your pup, but also keep him happy. [substeps] Make sure you spend at least 20-30 minutes walking your lab. Ending4: [substeps] If your dog hasn't developed its social skills yet, which is likely as early as childhood, it's recommended to walk your dog multiple times a day. [title] Make sure that your lab gets plenty of regular exercise.

Answer format: ending1/ending2/ending3/ending4