One aspect of GTA San Andreas that’s often neglected is staying fit and healthy. If CJ gains weight, the stamina will be low and run out fast. You can increase your stamina by 5% every 2.5 minutes of swimming. You can also get the same increase by running or cycling for 5 minutes. But, the fastest way to increase your endurance is using the stationary bike or treadmill at the gym. You will get a 4% increase every 14 seconds. Other ways include finishing the Burglar missions. The latter will give you infinite energy.