Caffeine or amphetamines? Just don't OD on 'em.
Sorry, more seriously though, your best bet is to be a little more physically active, focus on better/more sleep, and eat good food to help your body work well. Eat well, sleep well, move well.
Most of the 'energy' pills out there are mostly effective because of the caffeine, but it has a diminishing level of return (ie. you develop a tolerance for it quickly, and require more for the same effect). Amphetamines have pretty serious potential side effects, so in all honestly I can't recommend experimentation without medical supervision. Other options COULD include things like ginseng for immune support, rhodiola for chronic stress management, or possibly a small magnesium supplement to improve your sleep.
Outside of supplements and drugs, good lifestyle choices are your best bet. You can get a massage, begin spending 10min a day meditating, choose whole foods over refined sugars/preservatives, etc. Unfortunately, there are no quick fixes for this one.