Appearances are deceptive. An outward display of happiness can be complete betrayal while the lack of any external happiness doesn't mean that anyone is miserable. Many times, this comes down to the personality of the person.
From my own experience, I know that I cannot always be smiling though that doesn't mean that I'm not happy all the time. In fact, it's quite a narrow definition of happiness to believe that the outward appearances mean much to the inner workings of a man.
That's not to say that smiling, for example, doesn't help. The small connection with happy moments and smiling has psychological implications, and I imagine you could trick your brain into being somewhat delighted only by smiling. That's still no way to get out of being miserable.
This entire topic is faulty—if you're looking for visual indicators of misery on other people, the first question you should ask is not, "What can I see in others?" but "What does this search say about myself?"
For what difference does it make that someone else appears to be happy or appears to be unhappy? No difference to you. However, perhaps you can influence the force of misery with your visual indicators in one direction or another.
Maybe by smiling, I can make someone else's day a tiny bit better. I enjoy smiling back at another person, especially when they have no reason to have outwardly expressed such a profound and essential thing as happiness.
It's important also that I recognize your signals of misery. For example, when you are bored your mind wanders. This is visible to others whether you like it or not. It would take real effort to hide the fact that you cannot stand their boring story.
Why is that I'm so bored, though? Why can't I be present in the moment and listen for a bit? Why can't I occupy yourself with the subject at hand and make the "waste" of time come alive? This is, after all, your responsibility. It's not anyone else's job to make the minutes of the day pass for my benefit. Who is to say that all the "good" things I do aren't bad anyway?
I suppose it's me armed with reason, providence, morality, and philosophy. All the things that make up my reason, including my creator, tell me whether something is good—but those things also inform me that I cannot control the things that make me bored. I can't change a story to be more exciting or to have more drama to keep me interested.
However, I can make myself interested by using that moment to train myself in some skill or art. In the case of listening to a story, perhaps I'm improving my ability to listen—which I need to work on.
There you have it, no more misery.
Misery is failing to understand why everyone else is so happy.
There's a real danger in comparison of the self to others. It plagues us in many respects, especially in personal relationships and small groups we are close to. There's a constant competition to show everyone else, "My life is cooler than yours! Whatever you're doing is nothing compared to what I'm doing."
The solution to this competition is not to win it. It's to drop out of the game entirely and refuse to play by that scoreboard. That scoreboard involves a mix of money, appearances, people, and deceit—what good are these things in and of themselves?
(We could also argue as to whether or not they are wrong in and of themselves, but that's beside the point.)
The real wrong comes in the fact that there are so many people competing based on these measures. So, you've got to get out of it. You've got to get out of the rat race.
Does this mean you drop into another competition? Of course not. Another contest will have other contenders who you'll be tempted to put down and destroy in the course of battle. That is no path to peace.
How do you drop out of everything that everyone else seems to find important?
I don't think there's one easy step. It's a constant check. You check your desires at the door every time you recognize they are a distraction. In that case, you must develop your awareness and be able to see when your desires have become misaligned with a peaceful life.
For example, what is it when you are rushing that you seek to achieve? Much of it isn't even a desire to get where you're going—it's to get there faster than the people around you!
Your desire to do so seems to be natural and, thus, the avoidance of that desire will feel unnatural. You will have to force yourself to not desire the competition.
That comes down to a matter of habit. If your habit is to go at your speed and make sure that all of your actions and decisions are reasonable (with only the necessary regard for others), then you are on the right path.
Another example: When you feel the need to say something to prove your worth or increase your stature, remember the letters DNT. Do not talk. If you must, write these three letters down over and over on paper. It will seem like you are writing down what the other person is saying, and you will be less likely to speak.
The problem is not with speech, but with your motivation. Your motivation to speak is to increase your standing in the eyes of others rather than to provide value to the conversation. Do not talk.
That takes plenty of discipline and self-control, but maybe after a long while, it will become natural for you. It will become a default to not talk rather than to indulge in your speech. Your misery.
That's a fundamental tenet of misery—to follow it is to indulge it.