Everyone (well almost everyone if it's not everyone) has this trouble when they first start meditating.
It's something that takes practice, but you also should consider that "focusing" on something is what allows the mind to generate thoughts, so e.g. focusing on your breath causes your mind to think about the breath, often causing you to force the breathing into a pattern and then have thoughts about whether you're breathing correctly and "how long can I maintain my focus this time?" etc. The mind is a naughtly little trickster sometimes.
Have you downloaded Michael's free "Discover Meditation" course from this website? If not, I would recommend it. It uses mantra based meditation, which in a sense is similar to your repeating the "thoughts... thoughts... thoughts...." to yourself, but in a slightly different way, as you just let the mantra repeat itself, at it's own volume and speed, letting it come and go as it deems right.
Of course, thoughts will arise during meditation, including the thoughts that we are "not meditating correctly". Simply acknowledge that these thoughts are there, and invite your mantra to return, letting the thoughts pass by. Even physical sensations are normal, and likewise, recognise they are there and let them be, bringing the mantra back.
It takes practice, but you'll get there.
Hugs
Giles