Many live with the fear of going back to our old habits and ways losing all that we have done. Know that you have and will continue to do it. You will adapt what you do and find a balance to your healthy ways and life in general. Never live in fear but in confidence in what you have and will do!
The "fear" will be there for many and it is ok and will dwindle as time passes. Try and use it to motivate yourself in a positive way so you do not let it define your life but instead you define your own life by using this to your advantage.