If you are used to larger dose of caffeine as your stimulant, then you are probably desensitized. Also, the fact that you are drinking a hot liquid will tend to relax you. If I really need a jump start, I go with a Redbull, or simply a couple of cokes. Redbull provides you with a jolt of caffeine along with sugars AND the B-vitamine complex that is useful in breaking down those sugars and other carbs to produce chemical energy. So you get the stimulant and more energy. The problem is that you will come crashing down...
Ryan