Originally posted by Maelstrom:

Stamina management is a core mechanic in this game so I don't think a toggle is appropriate.

There is a mod that adds a sprint toggle to the game, and it works quite well. It just stops you sprinting when stamina runs out (and even has an option to set a stamina amount which to re-engage the sprint, if you wish).

There's no reason the game couldn't support the same thing as what the mod does, without the need for a mod. Sprint toggle is a pretty standard thing in games....even ones with stamina management.