Practicing gratitude is practicing yoga.
The yogis were very good at dealing with the mind. Most of our yoga philosophy is not about the body but about the mind.
The yogis realized that the mind was constantly falling down. The mind didn't automatically lift itself up and go towards the light. The opposite was true. The mind was never satisfied. Even brief moments of satisfaction were only followed by more dissatisfaction. The mind's natural tendency was to go towards darkness.
The yogis realized that the cause of this dissatisfaction was looking for happiness through the senses in the outer world. Even when one experienced happiness this way it was always fleeting, and was always followed by the same feeling of dissatisfaction afterwards. The duality was always present too. The ego constantly created the feeling of separation. The mind judged everything as good or bad. Things that were good, the mind attached to, and the things that were bad, the mind pushed away. Even the things that were good, though, ended up being bad shortly after they were experienced. The satisfaction was always fleeting. The mind was never satisfied.
The yogis realized that the secret to lasting happiness was to stop seeking happiness in the outer world and instead go inward and experience a deeper connection to the Self. This was the only way to find true happiness. This is why so much that we talk about in yoga is about going inward, quieting the mind, and finding stillness. It's in the stillness that we are able to experience a lasting happiness, and finally experience peace of mind.
Practicing gratitude is one of the ways we can practice being content. It is therefore one of the ways we can practice lifting the mind up. If the mind's tendency is to be dissatisfied then practicing being satisfied will help to break this pattern. Recent studies also show that practicing gratitude has a direct effect on brain chemistry. Practicing gratitude can help when you are trying to learn something new and lay down new neural pathways. When you are trying to replace an old pattern with a new pattern that will serve you better, practicing gratitude can accelerate your learning.
Hatha Yoga often talks about getting the energy to rise up to the sixth chakra. Most of us are living most of the time in the lower three chakras. These chakras represent our very selfish basic needs. I want to survive. I want to feel good. I want to have some control over my life. When the energy rises all the way up to the 6th chakra and we turn inward and experience a deeper connection to our Self, or, according to the Hatha yogi's, a connection to the Ultimate Reality, the yogis say we shift our perspective from being selfish, and living in the lower three chakras, to living in selfless service and looking at how we can be of service in the world and help others. We become more kind, compassionate, and loving. If when I reach the final destination I know I will become more kind, compassionate, and loving, it makes sense that if I practice being more kind, compassionate, and loving now this may help me on my journey inwards to experience this deeper connection to my Self.
Yoga is teaching us to shift from the selfish, ego, small minded perspective where we are looking for what is in it for me, what can the world give to me? Me! Me! Me! To a more selfless perspective where we are looking to see how we can be of service in the world, how can we help and give back to the world, and how can we help other people. This is yoga!
If you are complaining a lot, judging and criticizing yourself and others, you are aligned with the most superficial aspect of who you are, and identified with your ego. Try practicing gratitude! Be more kind, compassionate, and loving. Pretend you have already made the journey inward and you are further along on your path than you think.
Get on your mat! Do the work! You have the knowledge. You know what to do. Take the journey inward and experience a deeper connection to your Self. Practice yoga. Shift your perspective. Change your life!