So first thing, harden yourselves, like, sleep on a hard bed. Get up and shake yourself and go into the cold air and do your breathing practices. Wash in cold water. Don't always try to protect yourself and be in a comfortable, protected atmosphere. Expose yourself to hardship. That's what will give you vitality. All of these people dying of heart attacks: no exercise! They are also eating the wrong foods. Millions of people are dying of heart attacks, and it is simply the result of not understanding the most basic principles of life.