Many youngsters make the mistake of joining a gym before tuning up their body or legs for rigorous exercise. If your legs are not used to working hard and you start working out in the gym, your chances of getting disheartened are very high. Therefore, it is recommended that you strengthen your legs by getting used to long walks, some general exercises and gentle jogging. With the passage of time, you should be able to run for about 15 to 20 minutes.
Short distance sprints are a great way of building up your leg muscles. If you love athletics, you must have noticed that all world class sprinters have amazing leg muscles, which they have developed without working out in gyms. Start with 2 to 3 sprints a day and do 5 to 7 when your body gets used to it.
Having developed your leg muscles somewhat, you can start to sprint uphill. Try to run upwards on a bridge or a mountain if you can. Other than that, you should run through stairs, which put immense pressure on your legs.
It is recommended for beginners that they work on their upper body in the gym in the initial stages. Having developed chest, shoulders and arms, you can start leg exercises. You can discuss your goals with the gym instructor, who can instruct you about exercises.
Cycling & swimming
Cycling and swimming are also great work outs for leg muscles. Both these exercises put strain on each and every muscle of your legs.