Exercise is best when comprised of both weight training and cardio. A good start could be a full body program three times a week with focus on compound exercises for the biggest muscle groups topped off with 30-45 minutes of cardio two to three times a week, preferably interval training, it allows higher intensity which in turn heightens the effect and reduces the need for hours and hours of running. If you want more info on good compound exercises and interval training, there is a lot to be found around the web.When you run, mind the shoes and surface, if you're a bit heavy and keep running on tarmac, asphalt or other hard surfaces you're setting yourself up for failure from the start. This is another advantage of the interval methodology; the sheer miles you'll have to run for optimal results and subsequent wear and tear on ligaments, soft tissue and bone. Get good running shoes for your feet, not the ones that are cheapest or the ones that cost the most that will net the salesman the bigger bonus!
Diet is, as many have mentioned, very important to the overall result but also to how you feel on a day to day basis. For instance, a lack or imbalance of minerals and vitamin levles can lead to poor sleep cycles, low energy levels, numbness and cramps in muscles, lowered attention span and ability to concentrate, irregular appetite and other nasty things.
Make sure you get enough protein and healthy fat in your diet, both of which will not only ensure a better basis for building lean mass but will also give the sensation of being more full after a meal as opposed the typical carbohydrate-heavy meals. Carbohydrates also serve a purpose though, use it as energy and make sure to have a bigger intake of them before and after exercise to maintain energy levels in the muscles and prevent fatigue and soreness from setting in too bad (diet is paramount to getting rid of the soreness after a few weeks of training). A good meal has a balance of the three nutritional ingredients protein, carbs and fat. If you love fish; go for it! Its a good balance of fat and protein, allthough less on the protein than other meats. Chicken and turkey are also excellent choices, being low on unhealthy fat and very high on protein. Beware though, a fair share (roughly 10-15% in the West) of the population has trouble digesting and metabolising chicken proteins and is quite common along with lactose intolerance!
The number of meals per day is less important than their content, as is the time of day they are consumed. The general consensus is that one does not need 7-8 meals like bodybuilders do on a daily basis to have any kind of effect, they mostly do this to keep the protein synthesis high at all times and to even out the insulin levels in their blood. Regular people get along fine with 4-5 meals a day, and don't fall for the age old myth "breakfast is the most important meal of the day", all meals are equally important!
If you want to know more, there is a whole world of advice out there on the web, just check the sources! 
PS: I'm a personal trainer by profession (along with a couple of other things) so if you have any indepth questions, feel free to pop me a PM! 