Repetition gives intensity
In strength exercises you need to work the same muscles repetitively in order to get stronger. Language learning is a little like that. Athletes in all sports do repetitive exercises to increase their strength.
I have always found repeating effective. When I listen to content, I listen to the same content repeatedly. It helps if the content is interesting and the voice pleasant to listen to. When I listen I pick out or focus on different phrases or words each time. I then read that same content repeatedly for fluency in reading. I will review new words and phrases from that same content. I have saved these words and phrases on a separate list. (This is automated in The Linguist). Then I go back to listening and reading the same content again.
This is my strength training in language learning. It can be quite passive. I can listen while walking or jogging or even driving or sitting in a bus. But it is deliberate and is done almost every day during my period of intense study.
There other things we can do repeatedly. We can read out loud repeatedly, using a passage that we have been listening to. I would read the same passage out loud five times, exaggerating the pronunciation. Then I would record myself and compare with the native speaker.
It can be particularly effective to take some writing you have had corrected and read it out loud five times or so. Then record yourself and listen. This will reinforce the corrections and help your pronunciation at the same time. You will hear your own thoughts, things you wrote incorrectly, now expressed correctly.
You can even repeat in conversation. Try to make a three minute explanation of a point of view on a subject, after taking one minute to organize your thoughts. Then try to cover the same points in two minutes, then one minute.
All of these activities are like strength training . They prepare you for the more pleasurable activities of playing the game, or in the case of language learning, communicating in the language.