Prepare for a jolt

• A support that steadies or strengthens something else
• It's supportive
• Tone up, principally by running and callisthenic exercises
• "__ yourself!": "Get ready for a shock!"
• Support piece
• A structural member used to stiffen a framework
• Support; couple

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Brace \Brace\, v. i. To get tone or vigor; to rouse one's energies; -- with up.

Wikipedia Word definitions in Wikipedia