The first step in building up your stamina is performing aerobic exercises. These include brisk-walking, cycling, jogging, aerobic dancing and swimming. The second step is to take vitamin supplements since they function as metabolic regulators. Thirdly, ensure that you get adequate sleep and quit smoking, but that is if you do. Read more on http://www.livestrong.com/article/188677-how-to-improve-stamina-quickly/.