First off. Get sufficient sleep and eat well (this means lower the number of carbs, limit the sugar, get good amounts of protien and lots of veggies).
If those two things aren't fixed first, then no amount of working out will help.
Second, if you're interested in working out, start slow. As in, don't try to jump in and workout 5 days a week. You'll burnout and quit. If you don't workout regularly, a group workout setting like Crossfit is actually a pretty good way to go. People that cite injury rates around Crossfit tend to misunderstand the overall context. If you haven't done physical things for a while, you're going to hurt and most likely will have something feel like an injury. This is to be expected no matter what you choose to do. If you find a reputable gym with solid trainers they'll ask questions to understand your history and prescribe you the right amount of difficulty. The class aspect will push you and keep it social. Remember that if you're just starting out on something and you're new, working with someone that knows what they're doing is going to help a lot more than just trying to do something on your own and save a bit of money.
If those two things aren't fixed first, then no amount of working out will help.
Second, if you're interested in working out, start slow. As in, don't try to jump in and workout 5 days a week. You'll burnout and quit. If you don't workout regularly, a group workout setting like Crossfit is actually a pretty good way to go. People that cite injury rates around Crossfit tend to misunderstand the overall context. If you haven't done physical things for a while, you're going to hurt and most likely will have something feel like an injury. This is to be expected no matter what you choose to do. If you find a reputable gym with solid trainers they'll ask questions to understand your history and prescribe you the right amount of difficulty. The class aspect will push you and keep it social. Remember that if you're just starting out on something and you're new, working with someone that knows what they're doing is going to help a lot more than just trying to do something on your own and save a bit of money.