Get a Grip - English Idiom

Sometimes it can be hard to hold on to things. But what does the expression 'get a grip' mean? Watch this video and find out!

[evertonoliveira]

" Man, you're awake for more than 24 hours because of your SAT exam, I know you're anxious, worried and uneasy, but you must *GET A GRIP* ! "

Thanks ^_^