When you begin to worry, go find something to do. Get busy being a blessing to someone; do something fruitful. Talking about your problem or sitting alone, thinking about it, does no good; it serves only to make you miserable. Above all else, remember that worrying is totally useless. Worrying will not solve your problem.
When you can't do something truly useful, you tend to vent the pent up energy in something useless but available, like snappy dressing.
You have to be fast on your feet and adaptive or else a strategy is useless.
In this enlightened age, there are few I believe, but what will acknowledge, that slavery as an institution is a moral & political evil in any country. It is useless to expatiate on its disadvantages.
In preparing for battle I have always found that plans are useless, but planning is indispensable.
Computers are useless. They can only give you answers.
Just because something doesn't do what you planned it to do doesn't mean it's useless.
Nature does nothing uselessly.