How to make character run fast every few mins?

I want my character to be fast, every once in a while like sonic but i really dont know how. need some help.


So you want stamina? firstly make a number that can replenish. Secondly, make it lose value when people hold shift down, and increase the values of the movement numbers of which are being put into the velocity.

Thanks for that but I mean how the character starts out slow then a little fast then super fast.

Oh, that requires an ease, ease it down from a large number to slightly less so it starts off a bit faster.

Thanks for the help Sir