Do I need to micromanage my diet to get fit?

I've lost quite a bit of weight in the last year and feel like I'm in the best shape of my life. I normally do cardio/swimming at the gym but would like to start lifting and doing some toning.

I recently found this subreddit and after a quick browse, it seems like a "must have" to getting defined is to carefully count out what you eat? I'm all for lifting weights, doing crunches, and sticking to that, but I'm not sure I have the patience or dedication to micromanage what I take in at every sitting.