Mastiffs are incredible dogs. However, as incredible as they are they also come in an incredible size. If you have a Mastiff puppy and would like to walk him as he grows, you will absolutely need to leash train him. Some adult Mastiffs weigh well over 200 pounds and can overtake most of their owners quite easily. The way to avoid this from happening is to train your Mastiff how to walk on a leash properly. Leash training your Mastiff puppy will give him leash manners while he’s little, train him to stay with you with a loose leash rather than pulling you along, and teach him that you are in control even when a bunny crosses your path. He wants to play with you. He wants to spend time with you. You are his person, and he can't wait to follow your lead. Your Mastiff on a leash will draw attention and affection from others. Be prepared when you're out on walks, so he knows how to behave without becoming overly excited jumping up on people or knocking you over.
Leash train your Mastiff puppy as soon as possible. The younger and smaller your Mastiff is, the easier this will be. When you train your Mastiff puppy to properly walk on a leash, you should expect him to walk beside you in a 'heel' position, not pull on the leash, and even walk with a loose leash between you. If your adult Mastiff were to get away from you, oftentimes, the only thing you can do is let go and let him go. Proper leash training from an early age will stop this and keep him calm and by your side.
Mastiffs are large dogs. If you have a Mastiff puppy, be prepared for him to grow quickly. A Mastiff with a harness that connects the leash to the chest rather than the back is easier to control than a Mastiff with a leash and a collar. Your Mastiff is going to need to be entertained on these walks and encouraged to continue with training sessions. High-value treats are important to bring every single time you walk your Mastiff on a leash. Schedule your training sessions with few distractions. Over time, you can increase distractions.