Implant yourself an English brain [emoji]

Talking with native speakers will definitely help

What shall I do? Listen to English speakers all day. Watch movies with subtitles in English.

Most English speakers need 1000 hours of class and practice to become somewhat functional in French. Perhaps 2000 hours to become fluent. It takes less time with high quality immersion classes or high quality 1-1 lessons. I assume it's similar for French speakers to become fluent in English. A structured immersion program can help immensely. I met an English speaker who was somewhat functional in French after 10 weeks of 12-week French immersion program at a local francophone university. (He probably had had 300-400 hours of immersion).

Emigrate to countries that use English as public language.