That doesn't mean that upsetting things won't upset you, but it does mean that being upset won't be your underlying condition.
The doctor says she takes regular doses of her own medicine, despite what others might believe.
"People think I have achieved happiness and will always be in that state," she says. "But no - I used to be a child, then I became a teenager, and grew into an adult. I had relationships, then I became a wife. Now we have a child, and we might have another child. Every event in my life tested that default state of mind."
She says it takes real effort to avoid lapsing into an unhappy state, "but once you recognise true happiness, coming back to that default state becomes easy".
And, yes, she gets sad. "Things that get me down are usually when I see someone hurt." This means a day in the office can be challenging.
"People used to come to me for therapy, with one problem, but I could see the pain in the eyes [about something else] and I was itching to address that."
When asked about strategies she uses in such cases, Stoodley doesn't hesitate. "One of my clients struggled with being able to express their emotions. They thought they needed to be in control of their emotions because sometimes they bottled them up to a point where they had an outburst."
Stoodley taught this person that there is a spectrum of emotions and that although bottling everything up is definitely bad, letting everything out can be just as bad. The happy medium is to be aware of our feelings, "experience the emotion, and ride the wave. And then they have the time to respond instead of reacting."
"Responding" is the response of a truly happy person; "reacting" is the out-of-control response of an unhappy person. "Teaching someone to be aware is a lot of hard work. But once they get it, and they can keep reminding themselves to come back to the present moment, then it becomes easy."
Unlike others who acknowledge the importance of mindfulness and awareness to true happiness, Stoodley is not opposed to social media. She says it has a place in modern life. It's all about context.
"I encourage people to understand that social media is part of their entertainment," she says. "When they depend on it for their life, that's when things get out of hand."
In other words; it's not real life, it's a bunch of stuff chosen for you to look at by an algorithm that has worked out what you like. And that can mess with some people's heads: "Their perception of normal is actually created by social media."
Another contemporary social pressure that can make people miserable is the sheer amount of choice we have from social media sites, streaming services, online shopping and even dating apps.
Stoodley has a way to handle this in her own life. "If I have a project where I need to do some research, I could go on and never finish it because I could keep researching it forever. So I give myself a timeframe."
She sets a target, for instance, of two weeks to do her research and then calls a halt. In other words, she accepts that there will always be more, but enough is enough, a technique that can be applied to all sorts of choices.
Another obstacle to happiness that Stoodley confronts with her clients can be a feeling that they aren't allowed to be happy.
She says children's natural happiness is often shut down by adults "and that's where this guilt of being too happy comes from. 'Am I even allowed to be happy when my friends are depressed?'" She helps clients see that empathy for others' negative feelings doesn't mean we can't have positive feelings ourselves.
It sounds like it's all in the mind, but Stoodley says that's not quite correct, with recent research on the relationship between the gut and the brain leading to some surprising conclusions.
"We often say, 'I feel it in my gut' or 'I have a gut feeling,'" she says. It turns out those expressions describe something that is really happening. When you feel a threat, you don't think, 'I feel threatened.' You have an awful feeling in your stomach that you identify with being threatened."
Other emotions work the same way. "So, scientists tend to say that the gut has a brain of its own." To give a very simple example of the connection: "If someone has diarrhoea or constipation, they're not able to focus and think about what they're feeling. They just want the bad feeling to stop."
So, it turns out, being happy doesn't just take mental readjustment and awareness – it takes guts as well.
Three things anyone can do right now to improve their happiness, according to Dr Pamela Stoodley:
1. Be aware of what's happening in your life. Stoodley says it's too easy to go through life on autopilot, just putting up with things, and that stops us from making the most of opportunities to increase our happiness.
2. Don't repress your emotions. That means letting yourself experience negative feelings, but it doesn't mean indulging them when confronted with something you don't like. "You don't have to have an outburst," she explains, "Just stay with it, feel it, and then pause before you react."
3. Watch for patterns and bad habits. "People say, 'Oh this is how I am.' But cycles can be broken once you recognise them. Maybe you need to reach out to someone like a coach or a therapist, or anybody. There's no shame in that."
Cracking the Happiness Code by Dr Pamela Stoodley, Jane Publishing, RRP $29.99