I'm not against reading goals, and believe they can help if done right. But you need to set REALISTIC goals. If you're not used to read A LOT and, on top of that, you have attention span issues, your reading goal seems way too high!

How many books have you read last year? How is your routine? Do you work full time? Study? Etc.

Make yourself these questions before you set a goal. If you haven't read any book past year for example, and you set a goal of 6 books this year, this means that, if you reach your goal you read 600% more than last year, which is a huge improvement.

And if you read beyond your goal that's even better! There's nothing stopping you to go beyond it or even raise it after you actually got there.

But, specially if you have ADHD, setting up an unrealistically high goal will only make you anxious and frustrated.