It’s fine to listen, watch, and read English; you do need input. Talking and writing are fine, too. However, you need to make sure you are really challenging yourself so that you can get better. If you can read and understand this website then I am sure you can give your opinion and reasons for it.
There are reasons for this and none of them are new. The educational theorist Benjamin Bloom created a taxonomy (ordered list) of skills in order of difficulty and the lower skills are necessary for the higher skills.
Essentially, anything to do with reading and listening is a low-level skill. Repeating what was said is just a step up, organising information is the next step. The higher level skills are analysing information, using information to create something new, and making information-based evaluations.
By having discussions, you need to analyse information and make information-based evaluations. This could be as simple as comparing and contrasting two different songs you like and referring to examples to say which one is better, in your opinion. It sounds easy, but if you try it, it might not be.
Some different fora (plural of forum) that you could use are:
- the comments on this website,
- the comments on websites about things you are interested in,
- Yahoo! Answers,