I would recommend a product that contains NO(nitrix oxide). There usually used for weight lifting but they give amazing mental clarity without the use of caffeine. This is my product of choice. NO-Xplode by BSN:
N.O.-Xplode Highlights:
* Training energy, motivation and intensity
* Mental alertness and focus
* Muscle fullness, vascularity and pumps
* Strength, power, endurance and work capacity
* Resistance to muscular fatigue
* Healthy Nitric Oxide (N.O.) levels; blood flow and delivery of oxygen and nutrients to muscle tissue
N.O.-Xplode Benefits:
* Maximizes training intensity, energy and motivation; allowing bodybuilders to maximize muscle fiber stimulation
* Enhances mental focus and acuity; helps establish crucial mind-muscle connection for bodybuilders
* Increases resistance to muscular fatigue; preventing lactic acid and H (+) ion accumulation from cutting a set short of its full potential
* Elevates blood flow and delivery of oxygen and nutrients; aids in providing sustained training energy/intensity
* Increases power output and overall work capacity for bodybuilding training programs
I use this product and it's amazing not only for working out but for mental clarity. It's loaded with vitamins, it's better than coffee or redbull and only has 30 calories per serving! Hope that helps.