The biggest part of changing your lifestyle always involves changing your mindset. To change a mindset from one that perpetually sees the negative in any situation to one that sees the potential for the positive is likewise a gradual process. First you need to catch yourself out whenever you notice you are being negative. That in itself can take many months to learn to notice negative habits that you might have and it doesn't automatically mean that you will be able to see any positives instead for that too needs to be learnt and takes practice.
For the rest of the time we should be as we are now and function with our daily lives as normal. We should steadily and regularly review our progress only in our allotted time slot what we can try next to effect the changes we want to. When I embarked on this process is was with the aid of counselling. After every session of 40 minutes I would spend 20 minutes thinking about what had been discussed in the session and what my bite size targets were. As sessions were only once a week it meant that I had plenty of time to start to try out ideas for change in the interval between sessions. For myself I found that having a totally confidential (away from my personal relationships) sounding board to discuss things with was of enormous help.
All my best hopes and wishes on your journey to pastures bright, beautiful and new. Take it slowly to enjoy it.