under (one's) own steam
On one's own; with no assistance from anyone else. The injured player was fortunately able to walk off the field under his own steam. Look, Mom, I can finish this book report under my own steam, OK? I don't need you hovering over me correcting my spelling!
under one's own steam
Fig. by one's own power or effort. I missed my ride to class, so I had to get there under my own steam. John will need some help with this project. He can't do it under his own steam.