Classical Hatha yoga
Swami Sivananda (1887-1963) was an Indian doctor who developed a holistic yoga system based on the original Indian yoga philosophy. The goal is to develop the best possible physical and mental health. The yoga system is timeless and also fits modern yogis.
5 principles of yoga by Swami Sivananda
1) Correct exercise: Exercise that heals and strengthens the body without side effects, aka without breaking down the body. Sivananda recommended asana (physical yoga positions).
2) Correct breathing: We get more energy through breathing properly. We also increase the lungs' capacity so that the body can absorb more oxygen.
3) Proper diet: Food is something that gets accepted by the body, heals the body gives it nourishment, and fits with the composition of the body (everyone has different bodies, and therefore different needs). Food is everything that gets absorbed through the five senses. What is medicine for some might be poison for others. A proper diet is one that doesn't have side effects.
4) Proper Rest: – We give our senses rest. Often when we are going to relax we just move our attention from one (stressful) activity to another, for example, watching tv to relax. Proper rest/relaxation can be a power nap or yoga Nidra/ yogic sleep.
5) Positive thinking and meditation: Positive thinking and meditation help activate the parasympathetic nervous system, the body becomes calmer. Lots of negative thoughts increase the levels of stress in the body and lessen the effects of the positive changes we make. When we meditate/concentrate we try to "turn our senses inward", not to let the senses be active. When our senses are active our minds are active.