There are many situations that can push you strongly in one direction or the other. If you tend to see yourself as helpless victim, this is probably because at some formative point, you were victimized and helpless to prevent it. If you feel powerless to manage your own feelings and soothe yourself, you probably didn't have much help learning how to do that when you were young.
But history is not destiny. From a psychological point of view, emotional "reality" is the product of whatever story you tell yourself about how things are and why you are the way you are. If you want (or need) to change your reality, then change the story you are telling yourself. This does not mean denying or ignoring your past or present circumstances, or inventing a nice fairy tale to take their places. If you are a single parent with a full-time job, a person with major medical or emotional issues to contend with, or someone who is so large that physical activity is very difficult, this will be harder for you than for some others. You need to acknowledge that and be realistic about the changes you can hope to make and how easily you can make them. But you CAN rewrite your story so that these circumstances are not the determining factor in your success or failure. Your new story can be about how your creativity, ingenuity, and perseverance enable you to find full or partial solutions to these challenges, and to do the best that you can with what you've got to work with.
The story you are telling yourself at any moment is the foundation of your motivation, or lack of it. Make sure you are telling yourself the story you need to hear. And the best way to really come to believe your story is to see it come true in the small, well-chosen steps you take every day.