Imagine that you started to wear your wristwatch upside-down. At first it would seem strange and it would make telling the time slower than usual. Then, after a short time, it would become natural and you'd be able to tell the time quickly. The same rule applies to thinking in English.
If you are not in a situation where you can speak to other people in English, you should think about what you are doing in English. For example, when you are washing the dishes think about your actions in English.
The more time you spend thinking in English, the more your fluency will improve as you'll need less 'thinking time'. Translating from your language into English takes time, so it's better to get into the habit of thinking in English and not translating at all.
Give it a try!
