pull yourself up by your bootstraps
The self-help phrase, and what it first meant.
The phrase now means to improve your own lot without help. It first named an impossible act: you cannot lift yourself by your bootstraps. Do not use it as if the physics were sound. If you use it, use it as a figure for unaided effort, or skip it.
Examples
Use She rebuilt the shop without outside help.
Avoid She pulled herself up by her bootstraps and lifted the shop by its straps.