The Benefits

Yoga is beneficial for body and mind.

For example: It can relieve tension and stress, level out left and right imbalances in the body, increase concentration, as well as improve overall health and stamina, strength and flexibility.
Once the body becomes more used to the yoga practice, the focus can shift toward the breath. Distractions subside and it becomes easier to just be in the practice, rather than actively forcing the body or working strenuously.

Traditionally, asana (posture practice) was used to prepare the body to be able to sit comfortably for long periods of time with an upright spine.
It is then possible to focus on quieting the mind, work on concentration through pranayama and also to work towards meditation.