A practitioner of Hatha Yoga goes through three phases of practice. Sanatan Kriya details them as,
The First or the Beginner's Stage: This state assumes that the practitioner is a normal human being, who is attracted to the various aspects of the physical world, he wants to enjoy everything to the hilt, he wants to miss nothing, he wants to live life, which he thinks is life, to the fullest.
Yoga says why not? Go ahead, enjoy and go beyond, do not suppress your desires, go and sail in the ocean of life, but do not sink in it. Be like the boat which is in the water but the water is not in it, it sails through the ocean and misses no part of the ocean and yet completes its journey, experiencing the ocean in totality.
The beginners stage of Yoga deals with very simple asanas and pranayams, preparing you for the journey ahead; your vehicle, that is your body, is taken through etheric and physical purifications with the aid of yogic asanas, pranayams and shatkarmas. You are asked to leave nothing of the physical world; the emphasis is on purifying yourself so that the heavier things of life, which are not good for you, leave you on their own. As the body becomes subtler with the help of yogic purification practices, automatically the heavier things of life, which are not good for you leave you. A by-product of yogic practices is a light body, a clear and active mind, great physical and mental strength and balanced emotions. You feel as if you have been overhauled, and have gained a new body. Actually, the beginner's practices do give you a new beautiful body and mind.
Intermediate Stage: Now you are ready for the intermediate. The intermediate practices on the physical plane, give suppleness to your limbs, your bones are strengthened to prepare your body for long hours of meditation. Here dawns on you the meaning of Yogsutra 'Sthir Sukham Asanam' i.e. only when an asana is perfected do you feel bliss and stillness in that posture which is indicative of you having thoroughly gone over the yoni which that asana is indicative of. Now your mind is prepared for controlling thoughts and emotions. You are getting ready for awakening the Kundalini. You are preparing for the advanced stage through total experience and ananda. By the time you have reached here, the body and mind are in perfect harmony with each other. Some important asanas, which you would have perfected by now, are the Bhujang for the Manipoorak chakra, the Sarvang for the Vishuddhi chakra and the Sirsa asana for the Ajna chakra. An intermediate practitioner has total control over his body, mind and spirit. He is the master of shatkarmas (physical purifications) and disease or instability does not come near such a level of practice. Your digestion and evacuation is perfect, your control over the breath is perfect, and your physical strength is unsurpassed. Your eyes with the regular practice of Tratak are full of charisma, nobody can stare you in the eye. Anybody you look at with love is yours. You are a Jitendriya or the ruler of yourself. All your indriyas (sense organs) are fully under your control, you are in a perfect state of balance, disease and ill-health fears you.
Advanced Stage: At this stage a practitioner is introduced to advanced Yoga, as by now your body, mind and spirit control is perfect. So you are ready to awaken the Kula Kundalini or the force of Creation, which lies in a semi-dormant state in your Mooladhar chakra. As you have perfected the Siddha asana and the Ashwini and Vajroli/Sahajoli mudras along with the Maha bandh, the Guru gives you Shaktipath: the mother (Kundalini) awakens and begins her ascent.
You are given various mantras for various levels of evolution, which you would now go through, with the help of chakras at the various stages of your evolution. You are introduced to the various energies controlling the Creation and are taught how to harmonise yourself with them. You are taught the five states of matter and how to become one with each state. The advanced level is a level of pure bliss and ananda, writing more about it could confuse the reader so it is recommended that you search for a Guru and begin your journey now...before this yoni also goes by and you have to start again.