I got a bike recently, and before that I used to walk everywhere. I had classes pretty early in the morning a lot of the time, so i'd skip breakfast pretty often and it was never much of a problem. So today I did the same but rode my bike instead, and it was fine on the ride, but as soon as i got off my heart shot right up my throat and i felt like throwing up. Took like 5 mins of sitting down to feel fine again.