Is Krashen’s input hypothesis enough to reach fluency? Do you also need interaction in the language? Of course you do, and a lot. Input is powerful, inexpensive and easy to arrange. It can take you a long way. Eventually, though, you need to speak and even write, and you need to do a lot of it, in order to really improve in a language.But you can do it when you feel ready. The most powerful hypothesis of language acquisition is the enjoyment hypothesis. If you enjoy the process, you will have the best possible attitude, spend enough time, and notice what is happening in the language you enjoy. Here is a link to a video I did on the subject.