Get out of the house:

Browse a bookstore or go to the library.
Treat yourself to a cup of coffee somewhere where you can just sit and read.
Take a good walk every day.
Check your community for activities centers where you can go to exercise or take classes (often they are very affordable).

Find activities that require brain power and focus (on something other than your problems:

jigsaw puzzles
word puzzles
painting/coloring
gardening
board games

Many of these you can probably do with your siblings and it will be good care for them also.