Selfishness is combated through logical thinking. If thinking regulates itself logically, desires can no longer come up and the body works automatically. We close our eye automatically if a fly approaches it. Spirits of Movement built this reflex into us. What we do automatically is always correct and wise; what we do voluntarily is subject to error. Sprits of Movement also had to learn; they made a lot of mistakes before movements like eye closure became automatic in us and before these movements could be carried out so wisely. Such movements are completely independent of our personal feelings, wishes, etc. That's the way our thinking must become. The right sequences of thoughts must be strung together entirely by themselves; thoughts must not be produced for selfish reasons and purposes. They must proceed from previous ones in a purely logical way. We learn logical thinking from theosophical teachings, when the mighty facts that can all be understood with the intellect, even if one can't see and investigate them oneself, are placed before us and we try to grasp them with our thinking. Thereby we're diverted from lines of thought that only group around our own small lower ego and we're directed towards great, comprehensive ideas. That's the way we work on our astral body.
We're born with certain inclinations that become converted into habits during life. What fit to these habits earlier now becomes a hindrance to progress. All action must become conscious; we should do things on our own and not because of our connections with family, nation, classes or circumstances. Thereby we work on our etheric body.
Worries put pressure on the physical body. We should do our duty, and also against opposition, but we shouldn't worry too much. It's hard to strike the right balance here between concern and standing above it, but too much worry dries out the brain so that it can't take in new thoughts. The greatest man of sorrows or soter was Christ, and as it says in (I Peter 5:7) we should cast all our care on him; for he cares for you. that is, we should give all worries past a certain point to Christ so that He can make our physical body healthy and strong, so that our soul is also healthy.