Training your brain isn't impossible but isn't as quick and easy as it sounds....
Something you frequently come across when trying to find something to aid your chronic illness symptoms is meditation and mindfulness.
Meditation is harder than it sounds. Meditation is not just about breathing techniques and the position you are sat in. It's also about the surroundings you are in and how you feel mentally in the first place. If you are anxious, it will take longer to get into that relaxed state.
The most popular form of meditation, mindfulness meditation involves simply paying attention to your body—and nothing else. You might become more aware of the sound of your breath or the feeling of the floor underneath you, for example. If your thoughts wander to your to-do list or something outside the present moment, just observe that and try to steer yourself back to being mindful without judging yourself.
In this type of meditation, focus your awareness on one specific thing. You could zero in on the flame from a candle or repeat a mantra out loud, such as "I am at peace." For some beginners, having a point of focus is helpful in quieting the mind and relaxing fully.
In guided meditation, you listen to another person who leads you through your meditation practice. An instructor might tell you to focus on relaxing your toes, then your legs, and so on—all the way up your body. Or they might lead you through guided imagery, asking you to imagine, for example, a beautiful, white sand beach with water lapping onto the shore. Guided imagery can also be used for performance. For example, an athlete might imagine herself mastering a technical skill, or an executive might imagine himself confidently delivering a presentation.
A brilliant App that I used when I suffered from bad anxiety and lack of sleep is Headspace!
Headspace is an app that presents guided meditation. The audio is accompanied by short animations and its really easy to follow. However, after you have completed some of the meditation, they will urge you to subscribe.