I use on-the-go packets of energy drink powder that I drop into a small plastic bag when I travel. This allows me to have access to tasty caffeine anywhere I have water because I bring a bottle. Coffee does not offer the convenience or portability that energy drinks do.

I suppose I could bring instant coffee and drink it at room temperature or cold, but that seems sub-optimal.

I used to just carry caffeine pills with me, but people thought I was some kind of drug addict.