Here are some facts to know about your brain if you want to get more tasks done:
1. You can focus on only one conscious task at a time
2. Switching between tasks uses energy so if you switch a lot you can make more mistaks
3. Doing multiple tasks at once will lead to a big drop-off in accuracy and/or performance of those tasks
4. The only way to do two tasks fast and with accuracy is doing each one at a time (Rock, 2009)
Treat your brain well and it will do the same to you!