Animation of screen going blurry is annoying when you want to hold down shift to sprint to indicate that the player is tired. I should not get the annoying blurry screen after trying to sprint for more than 4 seconds. Not only does it not make it not fun to always have to stop/prone to catch breath, but lets be honest, these military guys in real life can sprint more than 5 seconds w/out getting tired as hell.
The animation for tiring blur is also annoying. At least make the blur take in effect of sprinting for more than 5 minutes( with a minute rest). The island is huge and not having vehicles will leave you running for hours on.