What do you need to create a Lesser Power that will toggle on and off?

Think of for example a Lesser Power that makes the player faster when you turn it on but when you hit it again it turns off the affect.

For that matter, what can make the player faster?

Thanks for all the help everyone.

I don't know for sure, but maybe take a look to see how Whirlwind Sprint handles player speed?

Well I tried adding a duplicate of the WhirlwindSprint Shout to the spelllist for a race Im playing/creating and it did nothing. It did not show up automatically in Shouts during gameplay. I also noticed that the spells which Shouts are linked to do not actually perform any task. They're just place holders for the animations associated with their parent Shouts/WordsofPower.

So it's a little confusing.