I made an addon that disables SharpeYe's stamina, but I've had reports that it no longer works. Try it if you want to, but it's better to make the changes manually yourself instead (and avoid issues).
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=1353416332

SharpeYe is a addon aimed to make Gmod more realistic by simulating head bobbing, breathing and all other effects. There is one major flaw however. The stamina module sucks. After 6 seconds of walking, you would be having a seizure and uninstalling this mod immediately. This guide will fix that.

To disable stamina, go to C:\Program Files
(x86)\Steam\steamapps\common\GarrysMod\garrysmod\addons
then find sharpeye_123514260. Drag that file to your desktop.

After that, unsubscribe to SharpeYe! If it is still subscribed throughout the next steps, it will not work!

Then, open your file explorer and find C:\Program Files (x86)\Steam\steamapps\common\GarrysMod\bin and look for 'gmad'.
Then, drag the SharpeYe file from your desktop onto that gmad exe.
There should be a new folder on your desktop called 'sharpeye_123514260'.
You can also delete the original sharpeye file (not the folder!)
After that, open the folder. Then go to 'lua'. Then open 'cl_sharpeye_base' and open it with notepad.
After that, press Ctrl+F and paste in 'self.dat.player_StaminaSpeedFactor'. You should find a peice of code highlighted that says 'self.dat.player_StaminaSpeedFactor = 0.01'.
Change 0.01 to 0.00.

Save the file, then exit out of notepad. We are ready to put this back into Gmod.

Grab the folder (sharpeye_123514260) and place it in C:\Program Files
(x86)\Steam\steamapps\common\GarrysMod\garrysmod\addons.

You have disabled stamina!
Thanks for reading.