I think it is very important while quitting to really look after yourself and here is a shortlist of my survival techniques. However it is not really survival anymore, it is the start of celebrating my freedom.
Try to see it this way, no matter how long you have ended the misery that is smoking. Even one a day will keep you in the loop, so don't fool yourself or underestimate nicotine.
A really nice treat is banana and berry smoothies with either cold soy or almond milk, with a good sprinkle of cinnamon. Or just a really cold glass of good quality/fresh orange juice. Warm water with lemon in it in the morning helps to cleanse your liver of toxin build up.
Walking is very beneficial for heart and lung health. As is swimming.
Simple meditations of around 10-20 minutes slow down the mental chatter and help with cravings and psychological addiction.
What nicotine does is explained well on this site but basically it is extremely habit forming and by quitting you are building new neural