The quick version: I pushed gently, drew back once it became counterproductive (eg, he became defensive or angry,) and then gave him some breathing room to process what was discussed. I had to break a pattern of just staying silent and waiting after I would push and he would promise that things would get better. Not always with another "push," but sometimes with flirtation or subtle reminders. It is important that you read your own unique situation and make wise judgements about which action to take at what time.
In my sitch, my H didn't begin to keep his promises of being proactive about change until I had a very important discussion about our marriage being at stake. Robx's post in this forum (found here: http://www.divorcebusting.com/forums/ubbthreads.php?ubb=showflat&Number=1754085&page=1) triggered me to say absolutely everything I needed to say before I allowed myself to detach any further from the marriage.
Of course, *how* you communicate is of the utmost importance (make it about "us," not just "me," coming from a place of "I love you" (even though you may have tremendous resentment.))
Please start your own thread so that we can examine your history and discuss possible pitfalls or suggestions for a new approach.
