The good news is “Yes, you can”! Below is a video from a polyglot explaining how.
The video is 17 minutes long, so to save your time I’ll mention his main ideas and develop them a little bit.
Repeating everything out loud from day 1
Use transcripts for audios or subtitles for videos and repeat many times till the pronunciation is comfortable for you.
Often, when students think of being able to speak fluently, they think of forming sentences and extracting vocab from their memory easily. But before all this you need to pronounce words correctly, fast and without effort. It usually helps to know how the sounds are made (=articulated by the mouth) and transcribed (you’ll see in a dictionary).
After words we go to sentences. There we need to take care of how words are put into phrases, the intonation (=how the voice goes up and down) and rhythm (=which words are stressed and which are not in a sentence). Also as you listen and repeat, pay attention to how emotions are expressed. Because it may be different from your native language.
Learn to “manipulate” what you hear
I’ll clarify: this is when you change a sentence just a bit, often to make it true for you. For example, if you hear ‘We’re going to the Alps for the weekend’, you can say ‘I’m going to the country for the weekend’ or ‘Unfortunately, we’re not going to the Alps for the weekend. I wish we were’ or ‘We went to the lake for the weekend’.
If you do it for grammar, it’s more like a drill exercise: ‘I’m going…’, ‘You’re going…’, ‘He’s going…’ and it helps you remember the form. If it’s for vocabulary, it’s a personalisation technique to memorise it more easily.
As you continue with “manipulating”, you go from sentences to dialogues. Often they can be found in coursebooks (audios) or grammar books. Or, in a video (like an interview). The technique is the same: don’t invent them from scratch, just change them a little bit here and there. Pretend it’s you and your friend in a dialogue. Add some real information. Now you can practise expressing emotions as well.
Talking to yourself or thinking out loud
The guy suggests that, because we practise speaking, we do all these manipulations orally. I’d like to add that it depends on your preferred type of perception. For example, I’m visual, and before speaking I prefer to have the new language written by hand. It is longer, yes, but it’s the only way for me to understand and remember it. You might want to include the writing stage as well, at least partly (I’m not suggesting you write everything you want to say).
From “manipulating” we go to describing your surroundings, your day, etc.
This is needed to build the vocab of your everyday life. I think we often forget about it when we want to learn ‘spoken English’, ‘slang’, ‘metaphors’, etc. Your life situation, you experience, your way of thinking are unique and it makes sense to first learn what you need to talk about them and then all those ‘cool phrases’ to get to B2-C2.
Talking to yourself is fine (we practise speaking). Recording yourself on your phone may be interesting (!), especially if you don’t mind listening to yourself. It’s a good way to track progress.
Personally, I also write diaries and it does help me to speak better because when I want to share something from my life I already have it structured and with the right vocab.
Having an emotional attachment with content
Emotions are key to remembering new language, so it is important to work with the material you like and engage with it emotionally. So whenever you watch something, you may have a short conversation with yourself – what’s the message of this video? what do you think of it? how do you feel about it? how does it matter for your life? Then you can ask and answer the same questions for different speakers in that video.
Keeping track of new vocab
As you come across some words/ideas you don’t know how to express in English, you do your search (Google Translate, Linguee, Reverso, dictionaries, etc) and add it to your notes. If you can’t find it straight away, leave out some space and make a mental note to keep looking for the natural way of saying this.
With this approach, when you finally get to speak to someone, you’ll have lots of your ideas prepared grammatically and lexically and you won’t find yourself in an embarrassing situation when you can’t find any words to express yourself. Worth trying!