​​Here is the research that links Daily Practice to reducing anxiety: 

Mindfulness
The benefits of yoga in children
Depression and Anxiety Disorders: Benefits of Exercise, Yoga, and Meditation
Mindfulness-Based Approaches for Children and Youth
The effects of mindfulness-based interventions on cognition and mental health in children and adolescents - a meta-analysis of randomized controlled trials
Meditation and mindfulness in clinical practice
Use of Meditation and Cognitive Behavioral Therapies for the Treatment of Stress, Depression and Anxiety in Students. A Systematic Review and Meta-Analysis

Exercise 
Association of Enjoyable Leisure Activities With Psychological and Physical Well-Being
Exercise for the treatment of anxiety in children and adolescents
Physical activity in European adolescents and associations with anxiety, depression and well-being
Associations between Nature Exposure and Health: A Review of the Evidence
Effects of Exercise and Physical Activity on Anxiety
Exercise in prevention and treatment of anxiety and depression among children and young people

Building the Staircase (Connecting logic to survival)
The Effect of Brain Teaser Games on the Attention of Players Based on Hormonal and Brain Signals Changes
Playing for Real: Video Games and Stories for Health-Related Behavior Change
Comparing the Effect of Music and Puzzle-Solving on Anxiety Before Surgery in Children: A Randomized Clinical Trial
Neural Substrates of Childhood Anxiety Disorders A Review of Neuroimaging Findings
Comparative efficacy and acceptability of bibliotherapy for depression and anxiety disorders in children and adolescents: a meta-analysis of randomized clinical trials
Bibliotherapy to decrease stress and anxiety and increase resilience and mindfulness: a pilot trial