Take It One At A Time

The reason why we worry is because we have so many things in mind. 
We think of food for lunch.
We think of the bad weather.
We think of the very hard assignment in Math.
We think on how to gain more money, etc. 
But here is the key.
You take them one at a time and you'll not notice it, you have solved everything for that day.
Take every problem one at a time.