Pick a mood. it could be angry, sad, optimistic, euphoric, excited, etc. write a paragraph in this mood about a subject that matches the mood.

for example, you might write about a high school senior who is optimistic about the future. the mood matches the situation.

Allie slouched in her chair, hearing the ticking of each passing second. It took all her will power to keep her eyes open. She had given up on listening to the lesson long ago. Her eyes had set on a whiteboard directly behind her teacher. Occasionally she would her numbers and random words her teacher was saying, but they dragged out into thin air, out of her grasp. Statistics, calculations, numbers... what a bore.

Hopefully this gets you started!