I came up with a very simple practice, which is this:
Be mindful of your body improving.
At first the mind will probably think: but my body is not improving. And that's the reason for the practice, to change that situation by using mindfulness and neuroplasticity.
"Neuroplasticity, also known as brain plasticity or neural plasticity, is an umbrella term that describes lasting change to the brain throughout an individual's life course. The term gained prominence in the latter half of the 20th century, when new research[1] showed that many aspects of the brain can be altered (or are "plastic") even into adulthood.[2] " --
https://en.wikipedia.org/wiki/Neuroplasticity" onclick="window.open(this.href);return false;
Improving the body will also lead to improved emotional and mental health. And this practice can be done even by very young people like teenagers who no doubt have bodies that they want to improve in several ways.
The idea is to be mindful of how the body feels (inner body awareness) and how the mind thinks of the body. And this mindfulness practice is repeated during the day whenever the practitioner feels like doing it, and repeated day after day for as long as it's needed to make the new way of being a subconscious habit.