Well, working out with weights would be great for you. Getting something like Proactiv body wash for the chest acne. You don't 'need' a 6 pack, but some toning to even the stomach out would help the look a lot. A little definition never hurts, but don't think you need to be built to be attractive.
You say you've been doing running, which is cardio and that's great and healthful. It burns fat and makes the heart stronger. But some sit ups and other ab and chest exercises would help a lot. But don't fret, you're not far from any goals you could set.