Your thoughts aren't going to go away. Not for a very long time. Right now, you're comparing yourself to the pinnacle of practice. You're beating yourself up for not being able to obtain something that's only available to people who have been sitting for hours a day and for years.
You can't force samadhi just like you can't force a flower to grow by tugging on it. All you can give it is the causes and conditions for success. If I could recommend a technique for you now, it would be simple breath counting. Just count your exhalations 1 to 10 and then start again at one. Just count. Don't worry about anything else that happens in between the numbers. Nothing that arises, positive or negative, is of any importance. Just keep counting, over and over. Get bored. Get antsy. Struggle with doubt. Get annoyed your racing mind. Let all of that happen, but keep counting. And try your best not to fidget. Start with fifteen minutes. Over time, try to add a few minutes until you can last for an hour.
If this practice frustrates and annoys you, if it makes you feel like you want to jump out of your skin, then it's doing exactly what it's supposed to do. When you reach that place of frustration - what one koan calls "the foaming billows" - persist, persist, persist.
Return to this place again and again. Over time, you'll start to grow exhausted with all your thinking and your doubting. One day, your mind will simply abandon these things itself. When that happens, then you've reached "just sitting". But for now, don't try to force it. For now, just make friends with frustration.
