Mischief may be done negatively as well as positively.

You never know how the team responds to that. They can respond positively or negatively. Their players might use that as something to lean on, to try to go out and play harder, or they might go into the tank.

It's important you think positively not negatively. Think about your loved ones and all the people who are behind you.

I solemnly swear that I am up to no good.

…for nothing is ever so mischievous in its own place as it is out of it;

Now let it work. Mischief, thou art afoot. Take thou what course thou wilt.