I'd get runner's high sometimes. If you got it, you'd know it. Personally, I only recall it happening for me at end of treadmill and erg and dumbbells session, not on any of the many runs on streets/waterfront/tracks.
The afterglow isn't confused with feeling good about completing exercise, or accomplishment/confidence. Example of confidence: when on a track, I'd run until I felt like I was out of steam, then sprint the last half-lap, just to know I could do that. (Don't try this if your heart isn't currently conditioned for it.)
I've given up caffeine, and hardly ever miss it.
One problem is caffeine for me seems to shift energy around, not create it. It might make me more energetic right now, but then headachey and ugh later. Also creates a dependence: "I feel like crap; I must need more caffeine".
Can also interfere with sleep many hours later, and sleep is super-important. It upsets GI a bit. And personally it seems to magnify some emotions, and, when caffeinated, I will somehow always find a cause of something that needs someone to fight for it (it's uncanny).
I care enough without chemically boosting things. And I'm fortunate to naturally be energetic and sharp without caffeine.
I don't drink even decaf anymore, because it still has too much.
IIRC, detoxing from caffeeine cold-turkey takes a couple weeks. Or zero-caffeine herbal/fruit teas can help with the warm mug of hot liquids ritual substitute. And exercise, hydration, nutrition, and good sleep.