I'm 55 years old. I work a second shift job 2pm to 10pm, and want to go to the gym after work. I'm on my feet for the entire shift at work with moderate physical activity. By the end of the shift I feel very tired, and don't have the energy for the gym. What supplement(s) can I take toward the end of the shift to energize me? I mean, really seriously energize me. Going to the gym at some other time is not an option.