You might take this with a grain of salt since it's coming from a skinny dude who works out for reasons other than weight loss.
There's nothing wrong with a half hour of cardio at a time. There is such a thing as too much cardio, especially if your diet isn't planned around supporting a lot of activity. Even if you're not into weight lifting or body building there's plenty of helpful information here:
http://scoobysworkshop.com/does-cardio-burn-muscle/Muscle burns more calories than fat, so more muscle = you burn more calories even when you're just sitting.
Something to combat the boredom factor could be high intensity interval training. Sorry to throw another link in here but I'm rubbish at explaining and don't want to accidentally give oversimplified or bad information:
http://en.wikipedia.org/wiki/High-intensity_interval_trainingFor cardio, I do different stuff, which helps minimize boredom. Yard work. Long walks. Dancing for 10 to 30 minutes to fast techno on youtube. There's tons of music on youtube and some of the videos are convenient workout lengths, so stopping to pick another video is avoidable.
Eating spicy food is supposed to help metabolism a bit too, if you like hot peppers it might be worth it to work them into more meals.
Editing this in, a digital food scale combined with reading nutrition labels makes a huge difference. What I used to pour for "a bowl of cereal", not knowing how much it really was, probably double or more what I pour now that I can measure and choose how much I need.