Unfortunately I am going to have to disagree with the previous comments.
There is no way to spot-reduce AND there is not a way to 'target' your lower abs. Your rectus abdominis (which is the muscle that shows you the famous 'six pack') is ONE muscle that only appears to be divided. A fibrous connective sheet (think of the plastic on a six pack of cans) holds the muscle in place and gives it the six (sometimes 4 or 5) distinct looking muscles. When people refer to working their lower abs (such as leg raises) they simply recruit the hip flexors to do some (or most) of the work.
If you are trying to get rid of the last few inches or that "pooch" that everyone refers to consider this:
Your diet has to be intact!
- Try cutting carbohydrates (especially simple carbs) the last 3 hours before bed. Carbohydrates (energy) late in the day will result in an insulin spike and later fat retention.
- Increase your fiber intake and limit red meat to once a week. It can take red meat (pork, beef, etc) up to 3 and 4 days to fully digest and guess where it sits? In your intestines which can make you look bloated. The average person can hold (gross) around 8 lbs of waste in their digestive system at any time. Eliminating saturated fats and red meats combined with proper fiber intake (around 25 grams per day) can help get rid of some of that unwanted weight.
Work your larger muscle groups!
- To get rid of 1lb of fat you need a calorie deficit of 3500. And while working your core is important (for postural reasons, etc) you should focus on multi joint movements that work your legs, back, or upper frontal torso (chest, shoulders). Jump squats, push ups or rows will burn many more calories than your traditional crunch
Choose the correct type of Ab workout!
- Focus not on your outer, but on your inner layer of abs. When doing a crunch you work primarily your force producers (rectus abdominis). Try doing a plank! As your inner (underneath layer) abs get stronger they can literally draw your stomach in.. at least to some degree. So the saying "suck your stomach in while you're driving" has some validity.
- Do functional abs. A burpee: you work your abs AND the rest of your body for tons of calories.
Sorry for the lengthy answer.
Have fun and good luck!