This is a worry jar, if you are feeling stressed and worried about something then put it in the jar by writing it down. The top of the jar is sealed so that the worry cannot get out of it. Once it is locked in the jar it is time to think about the positives and negatives of the worry.
There can be positives that come from a worry, just think really hard, write these down and use two different colours to write them down, choose your favourite colour for the positives and another colour for the negatives. If you want, you can even share your worry with someone else so that the can help you, but you have to be comfortable to do this.