Just as overt aggression doesn’t achieve much in the long run, the same goes for being passive. The most beneficial place to be is one where you know how to assert yourself where it is needed and then take a step back and let others share when they need to be heard.
Firstly, assertiveness comes from knowing that what you have to say is important and it counts. If you believe that your ideas don’t mean much and no one will want to listen to them, you’ll go straight into passive mode and afterwards, the chances are, you’ll end up regretting it. Thoughts like: “Nah, that’s stupid, if I say that people will think I’m silly!” Will naturally cause you to pull back and regress into yourself. So the next time you notice yourself doing that you’ve got to break that habit and say to yourself: “I’m going to share my thoughts and ideas because I count and they are great ideas!”
Validate yourself, thought and ideas on a regular basis to get yourself into the habit of creating a more assertive thought pattern and hence becoming more assertive in your day to day situations.