Drivers

I would suggest going to see a teaching pro at your local course. They can put you on a trackman and see why you are not getting the most out of your Driver. It may be a simple club adjustment needed or something in your swing. By going to a professional they can figure it out very quickly.

You tube has many great videos of common driving mistakes and corrections.

Chuck is right! Start there. This will tell you launch, swing speed and carry. Could be a variety of several small things to help you pick up a significant increase.

If you are looking to gain distance through working out focus on your core, forearms, and trunk. Golf you want long muscles not big muscles. Big muscles will hinder flexibity which is key in maximizing distance!

To add to Chuck's comment, after your swing has been checked, you might need a driver fitted to you. 90%,of golfers buying off the rack have sub-optimal equipment

Thanks for all the feedback everyone!