Good for you Illini, if you are like me as gamblers we tend to have an addictive personality so when I do something I tend to really focus on it like exercise. Gambling not so much anymore, life and kids gets in the way of that.
My advice, anything is better than nothing so ANY exercise is better than nothing. As we get older it's gets a lot harder, I do weights over my lunch hour, cardio in the evening. I do not workout 7 days a week, your body needs time to recover. Doing all cardio and no weights wont' burn fat near as well as doing both but if you are trying to lose 100 lbs that's a little different story. At your weight loss goal I think 5 lbs a week is do-able but really slow that down as you get closer to your goal. 1-2 pounds a week is what I would aim for if you truly want to lose it and keep it off.
Once you get doing something (I don't know what your level of fitness is) make sure you switch it up and doing different things. If you do an elliptical do it at different speeds, different distance, different intensity, etc. What I mean is don't set it on a single speed every workout, for the same amount of time everytime. While again that's better than nothing, your body will get used to it. I run, I bike, I sprint, I do some of the P90x cardio stuff, Insanity, etc and see great results. I know someone just starting into a fitness routine can't do all of that but down the road I would. There is a reason people see immediate great results from P90x and insanity not because they have some magic workout that has never been done but they really break down a lot of different things that your body hasn't seen at the same time and they keep changing it up and get your heart rate up. Nothing people can't do on their own, but I see some guys at my gym that do the same routine every single time and then wonder why they don't see results or they don't push themselves.
Agree with a couple others who said plan your meals but don't be so strict that you never cheat. Shock your body that way too and eat McDonalds or something you love sometimes too.
Good luck!