Go to the designated gym (usually near Vespucci Beach or Mirror Park).
: A Citizen.Wait(0) ensures the command executes every single frame, making the stamina essentially "infinite" by never allowing it to drop. Server-Side Nuance fivem infinite stamina verified
Many high-population servers (often inspired by NoPixel or QBCore frameworks) include a inside their F2 or F5 character menu. You might have missed it. Go to the designated gym (usually near Vespucci