I would add one thing which, I believe, is vital for strengthening immunity. Charging yourself with positive emotions.

The good mood is most important for growing. Only here you can open your eyes wide enough to clearly see your goals, and your actions become inspired, not something forced by your will or the feeling of inferiority. It softens the effect of bad news and helps to look at possible crises constructively.

I see two ways to do that.

First, via waking up previous experiences – recalling something good from the past (a way to make it live with you longer too), or just looking back at your day, as it goes by or before going to sleep, and spotting what made you feel good, to any degree, in any respect. And here comes the coolest thing – the chain reaction: one nice thought wakes up another one. (Works perfectly both ways, so not to try with those of the opposite kind! :P)

Second – via your present actions: noticing and intentionally doing things that make you feel happy and thankful. Att least something every day. E.g. something of this. In some exquisitely blue moments it may seem that nothing works… Haha, this means it’s right the time to try more ways! Something will work for sure, and you’ll end up with a box of new tools to use in future, and not only for yourself.

The important thing here is consciously fixing this state in your heart and mind every time you feel it. Like ticking your inner box ‘Now I’m happy’. Being consciously present in this state helps you to fully savour and get the most of it.

Somebody said, ‘You are a king of your life if you can rule your mood’… Experiencing and fixing positive emotions makes it easier to summon them when needed. Ideally, this should become an autopilot. And I believe this is the best shield. This is actually the immunity. Surprisingly, in my darkest moments at some point my mind drove me to most precious things in my life, and that was what kept me going.