7 Reasons as listed by Forbes here

• Meditation Helps Preserve the Aging Brain

• Meditation Reduces Activity in the Brain’s “Me Center"

• Its Effects Rival Antidepressants for Depression, Anxiety

• Meditation May Lead to Volume Changes in Key Areas of the Brain

• Just a Few Days of Training Improves Concentration and Attention 

• Meditation Reduces Anxiety — and Social Anxiety

• Meditation Can Help with Addiction