From Time.com here are 10 excuses unproductive people use:

1. I'm overworked

2. That's not my job

3. I'll finish that later

4. I don't have all the answers yet

5. I'll wait for the bosses to tell me what to do

6. I don't understand all the variables

7. I don't see how it benefits me

8. I might not get the credit

9. I'm worried about the quality of my work

10. I'm afraid I'll fail