[duh]

If you can't focus on it, it must not really be that important.

Quit your job and make it your means of survival.

If you're a student, focus on your schoolwork instead. If this IS your schoolwork, consider switching fields.

[sambirch]

Being unable to focus can simply be a side-effect of being distracted, tired, or trying to learn something that really pushes your brain.

The fact that you have a hard time doing something does not mean you should give up on it.