When a Guru is found, their guidance expedites our spiritual progress in an unimaginable way, in a way that is virtually impossible to achieve through our own efforts. Only you can know who your true Guru is based on your inner conviction when you are in their presence, or if that is not possible with their writings and photograph.
Having a Guru is not something strange or to be feared, it is a natural and normal part of the development of our Yoga practises. As we take the help of teachers for everything else we do in life, so too we need a guide for the Yogic journey. Someone who knows the way and can help us avoid the obstacles and pitfalls.
Having a Guru helps us to feel the nearness of God in our every day lives, so that God is not just a distant reality, or a mere concept. The Guru teaches us to develop our own intimate relationship with God that is very tangible. The Guru will over time feel like a close divine friend, who is always there for you and wants only for you your highest possible good. The very heart of Yoga is Union with God, and this is precisely what the Guru strives for us to experience and achieve.