Your environment impacts your mood. Create an inspirational area where you spend your most time.
You cannot avoid difficult people but you can learn to deal with them. Take some people management training if necessary.
Write to yourself to help overcome any lingering doubts or issues you’re still holding on to.
When you find yourself losing focus, ask yourself “why?”. Once you know, you can improve your strategy.
To get another perspective, ask for feedback from friends and family.