Most people think tennis is an easy sport, not so and certainly that is not the case if you play to win and slaughter your opponent in a gentleman like fashion. Playing a good round of tennis with a younger, more agile and better conditioned competitor is difficult indeed.
But luckily impetuous youth will show its true colors if you have your game plan down and are sure footed on your fundamentals, then capitalize on their trick shot mistakes. Yet even in doing this the key is endurance, because once you get too tired you ability to compete with the youthful agility is severely hampered.
So then what can you do to increase your stamina and endurance in tennis? Well playing often 3-4 times per week helps, but it is even more than that. Sure you can go to the gym, jog and stay active, but realize in tennis these are different muscle groups and so you need to make sure you are hitting them hard and building them up.
Most of all good stretching exercises will help you from soreness and early fatigue both in practice and during the game where you show that youngster who is boss and beat him in straight sets.