Halo 3 Achievement Problem?

[Reflect The Storm]

I am trying to get the achievement "Marathon Man" by locating and accessing all the terminals in the game... I have done this threee times and it hasn't given me the achievement. I have accessed all of them and waited until the green arrow turned red then exited and I still can't unlock the achievement.... What am I doing wrong???????

 

[furiouski]

you gotta play outdoor sports such as basketball or soccer, halo is okay for a while

 

[Hang 'em High]

Heres an Achievement Guide

http://www.gamefaqs.com/console/xbox360/file/926632/50375

Also, you shouldn't exit out right after it turns red, there is text after that too. Stay until the very extreme end.

 

[okicabana]

check a video on youtube to see were they are you might have missed one