Fair warning, though, on the off chance you're already ADHD... Mindfulness is the exact opposite of helpful for most (ADHD) people / can* make things exceptionally difficult/worse... As one is already constantly aware of everything and the struggle is to filter all the incoming messages. Not track down even more!
The parallel is a radio. If a neurotypical (or straight up PTSD, depression, etc.) person can only hear something of an annoying whine, mindfulness teaches people to turn the volume up... So they can actually hear the song. For someone who is ADHD, the 'annoying' buzz is the blissfully muted sound of 50 stations playing at the same time, that one has to expend rather a lot of energy on a daily basis to ignore. Turning up the volume on all 50 stations? Puke. ADHD meltdown cometh. Or total disassociation storm.
ADHD is only present in something like 4-6% of the population, so the likelihood of Mindfulness being a problem instead of a solution is slim. It will probably be a benefit to you. I just like to periodically throw out there, that while certain things can be hugely beneficial to most, little or nothing is beneficial to all. ADHD peeps generally* should avoid mindfulness like the plague (like gymnasts & yoga), etc. Ballpark numbers, but on average if 80% of people respond 1 way, there will be a number of groups hat make up the 20% that respond the opposite or in oddball ways. Just like taking meds. Ideally, the mindfulness psychologist will be aware of any exclusion groups that don't respond well to their paradigm. If so, don't fret. It's nothing personal. Just human nature, and the dizzyingly divergent ways in which we are all different :)
* I use words like generally, can, tends to, most, etc... Because scientifically there really are outliers in every group. I know hundreds of ADHD people who have tried mindfulness, and loathed it (for the exact same reasons) and a small handful who love and adore it. <Chuckling> Which just loops right back into the "nothing is true for everyone" theme of this public service announcement.