This whole process sounds strange from the outside observer, so it is time to stop being one and really give it a go. It will seem odd at first, especially if you aren't used to hearing encouragement from anywhere. If this is the case, it is even more important that you become the one to take over this role for yourself.
Life will continue to have difficult moments. It's the only way that we would ever become better, as we rise to meet each situation as it comes. Coach yourself through them. Encourage your thoughts with optimism and faith in the best parts of yourself. "You can get through this tough moment, and you are getting stronger by not giving up." "You get things done. You can do/create/have whatever you want." "I believe in you!"
You always have the choice of what to think and say to yourself. Coach yourself to success and new heights. Coach yourself into actually GETTING to the gym, during that workout once you get going, in your role as you parent or partner, and in encouraging yourself to eat right. Start now, and say to yourself in this very moment, "I can do this, and I will!"