Lack of Attention span.. leads to frustration and Anxiety. Symptoms of ADHD..?

I have an attention span that chooses whether or not it wants to work.

Sometimes I could focus on something long enough when I want to, achieving it easily, an example would be video games, football, or anything else Im interested in.

However, when it comes to revision, my mind gets lost and becomes distracted VERY easily. This eventually leads frustration as the stress mounts, which then leads to anxiety, and after 45 minutes of little work, I give up.

I've always also thought that I have ADHD aswell, an example being during the church the other day, it was in French (I only speak English) and my mind was driving me crazy.. A long period of time of pure boredom and I felt like smashing something, I was fidgeting all over and was incredibly anxious (When I used to line up for class when I was younger, I would fidget a lot aswell)

Help me.. Any more details? Ask away..