If you have a Shih Tzu that loves to jump in your lap all the time or paws at you, this does not necessarily mean that he trying to do anything bad. Rather, it may be your dog's way of saying, "I need to play and exercise!" When this happens, go on a good walk with your Shih Tzu. In fact, to cut down that continual pawing and lap jumping, incorporate daily walks a few times a day if possible.
It is also important to try and read body cues. Sometimes, your dog is not misbehaving but rather trying to tell you that something is not right. It could something simple like your Shih Tzu needs to go eliminate or he needs more water in his bowl. Recognizing that your dog needs you is crucial. The Shih Tzu is very smart but cannot always communicate what it needs.
A Shih Tzu wants nothing better than to be by his master's side all the time. That is all fine and good. However, did you know you are almost setting him up for failure by not attending to his needs before you get involved in a project, whether it is work or reading a book? If you take care and get him his favorite chew toy or fill his water bowl or whatever before you start something, chances are that he will not bother you or cut into your project time. He will be content just lying next to you or being in the same room.
When you sit down for a while, instruct your Shih Tzu to lie down near you. Most Shih Tzus will automatically do this. However, if they have a pressing need, they will not until it is taken care of first. Often, if you make the effort to see to their needs first, they will likely just lay down near you. Don't forget, your dog wants nothing else except to be near their human masters.
Some Shi Tzus are naturally a bit high strung and need some time to expend that excess energy. Arrange a play date with another dog or hook a leash on him and take him for a long walk. Once your dog winds down a little, you will find that he is a lot more agreeable in his behavior.
Shi Tzu puppies appear to be little balls of fluff in perpetual motion and they are very inquisitive. They will seem like they are into everything and that is normal, just a part of being a puppy. However, as they get older, most of the Shih Tzu are content to relax all day. Of course, with behavior modification, training should start with they are still puppies. Be advised that it will take a bit longer simply because they are puppies.
Just remember that most of the Shih Tzu, while active, is not hyperactive. Don't try to "give him something" to make him calmer. That may do more harm than good. With proper training and the setting of limits, they can catch on quick to your personal routine. They are smart and inquisitive, absorbing all the stimuli around them. Be careful though. They can be stubborn little tyrants so you have to show them right away that you are the leader.