Increasing stamina in Grand Theft Auto V (GTA V) is achievable by consistently engaging in activities that require its use. The effort to build stamina may take time, but with regular practice, it should noticeably improve. 1. **Running or jogging:** This is the simplest way to increase your stamina. Whenever possible, make your character jog or run instead of using vehicles. Start by sprinting short distances and gradually increase it over time. 2. **Swimming:** Swimming is another way to effectively boost stamina. Locating a body of water like a river or sea and going for a swim can help increase stamina. It works similar to running: the more distance you cover, the better. 3. **Cycling:** Use bicycles whenever possible. Cycling also contributes to stamina gain in the game. 4. **Triathlon Races:** Once unlocked, participating and completing triathlon races significantly enhance your character's stamina. 5. **Story missions & Strangers and Freaks missions:** They often have running, chasing, and other physical activities. Try not to skip these activities as they contribute to increasing stamina. 6. **Practice Yoga:** Practicing Yoga with Michael De Santa at his mansion also adds a bit to your stamina. So, don't skip such events if you're playing with him. Do remember that the rate of stamina increase would be naturally slower in the beginning. Don't be discouraged, continue to indulge in these activities, and you would see gradual improvement in your character's stamina.