What is the best way to stimulate a tired mind and body?

Between school, work, and social life, a typical day in modern society can be exhausting; sometimes from lack of sleep or just plain stress. I want to know what is the safest, most economical, most reliable, and effective method to feel energized and focused when sleep is not an option. Is it drugs (i.e. caffeine), focus games online (i.e. luminosity.com), certain diet, types social interaction, or something else?