I have a nondisplaced fibula shaft fracture. What now?

Keep off the foot. If fracture is non displaced then best to keep ankle immobilized in a cast for 4 weeks and transition to a fracture boot for 4 weeks and transition to walking thereafter. Range of motion can begin at 6 weeks after fracture. Serial x rays are necessary to evaluate fracture healing.
Use it! A non displaced fibula shaft fracture does not require surgery or immobilization. You may use your leg as tolerated. .
Fibula fracture . Generally speaking no displaced fractures can be casted for 4-6 weeks. If the fracture is however noted to be unstable or in combination with other injuries that would render instability, surgery may be indicated.