Feeling like you don't have control over your life is sickening now is the time to seize the day.
First sit down and talk with yourself on whats bugging you about your life. "yes with yourself"
Come up with ideas or ways that a person who you see as strong willed or confidence would deal with the problems that bug you.
Use the Ideas you come up with and modify them so that you are able to complete them.
Whenever a problem arises try to see it as a challenge like a challenge you might experience in a puzzle or video game and try and over come.
At the end of the day look back at what you did and be proud and look back at what you weren't successful at and realize you will improve if you keep trying.
Kick your bad habits by creating new good habits.
for example hide a small portion of your favorite snack in your workout room so you are at least tempted to work out when you want your snack
Improve your skills.
Look at things you do each day and try to improve your skill at it.
If you sing in the shower sing out of the show and try and practice.