Stoicism is ultimately a worldview about how to live well. It's focused on taking responsibility for what we can control and cultivating excellence in our thought and action.
How do Stoics do this? Through a variety of contemporary and ancient tools.
Negative visualization
Recognize that things can go wrong. You may lose what you value. Obstacles may arise. Imagine this happening. Why is this helpful? First, it's critical for planning. If you preemptively consider what may go wrong, you can improve your plan. Second, when things go wrong the default experience is to be disturbed and shaken. With negative visualization, we can rehearse facing and conquering obstacles.
View from Above
With the view from above meditation we move into a third person perspective. We consider our role in humanity: we are just one of the thousands of people living in one of the thousands of cities. We consider our place in time: there have been billions of people before us, there will be billions more. Eventually, all will be forgotten. With this perspective, what is important to us becomes crystalized, what is not falls away.
Journaling
Stoics cultivate honesty about their own lives. This means summarizing what happened on each day, where they acted with virtue and where they acted with vice. In order to improve, you need to know what's going on and spend time reflecting on your life.
Mindfulness
Mindfulness meditation can be a gym for practicing the Stoic techniques. Importantly, it will help you get better at accepting what is out of your control and getting distance from your thought.
These are just the beginning. Watch this space. Look into Stoa if you’d like to start practicing now.