On Tisha baAv you can't 

1. eat

2. wash oneself 

3. anoint oneself

4. marital relation 

5. wearing leather shoes 

6. sit on a chair 

7. Torah study 

8. greeting people with a blessing 

9. conducting business 

10. going on a pleasure trip. etc.

So my question is, what are you supposed (or what do people) do for 25 Hours. Besides maybe 3-5 hours of davening and 8-9 hours of sleep coming out to about 13 hours of...