In the same way that there lots of shades of grey between black and white, there are lots of yoga practices which are a combination of the two principle types: physical and mental. Mental or Raja Yoga is largely about seeing life differently – beginning with yourself.
Here’s the short version:
You can’t count and recite the alphabet simultaneously because your brain thinks single, consecutive thoughts (similar to the way your heart beats and you breathe).
But when you silently count “1+1=2”, two things do happen simultaneously: the counting – and the awareness of the counting.
Yoga is based on the premise that your awareness (aka your consciousness) is not a mental function; rather, it’s a separate and distinct part of you – the way your body and mind are distinguishable parts of you – but unlike your thoughts and physical body, your awareness never changes. It can’t because it’s simply your awareness or perception OF something – not the cognition and judgement which follow; so there’s nothing to change. This is the distinction between mind and consciousness: the former functions while the latter simply exists – universally, yet separately within each of us. Without awareness, we’d all robotically go about our business – unaware as we were doing so!
The stated objective of Yoga is to self-identify with your awareness rather than your body/mind. The Yoga Sutras include an eight-step proof that your consciousness is indeed distinct from your mind. Few people get to that point in their practice, but the mental and physical benefits of trying are cumulative and hugely rewarding/calming.
The first five steps essentially prepare your mind to meditate – and the last three steps are meditation exercises. Of the five preparatory steps, the first two which address personal conduct (essentially “be a good person”) account for 70% of preparing to meditate – the next three steps (posture, breathing, and concentration) only account for 30% of preparing to settle your mind. The implication is that your conduct has twice the impact on your state of mind as stretching, breathing and concentrating!