Self (atma) is one's real guru and guide and atma is Shiva

"Those who investigate the nature of this world with their own efforts manage to lift themselves up even without the help of a guru. The self (atma) is one's real guru and guide, and man is fully capable of arriving at his own good by both direct
perception and inference." ~Shrimad Bhagavata Purana: 11.7.20

There is so much confusion about guru. Guru is teacher, plain and simple. Anyone can be your guru - anyone you learn anything from IS guru. Hopefully, if we are learning, then our life is a continual procession of different gurus of all shapes and forms. The shastras glorify the Satguru - i.e. the person from whom we learn about spirituality - and say s/he is to be revered. But it's important to realize that even if we are not aware of a specific spiritual teacher in our lives, we still have many gurus. Just pick one ;-) Gurus are manifestations of God, Siva, Atma. They come to us and teach us. We learn when we humble ourself (i.e. ego) before something greater. This humility is what attracts the Lord's grace. As my teacher says: God's grace is like water; it flows only to low places, not high ones. If you want grace, make yourself like a valley or well (humility, surrender), not like an outcropping or mountain (pride). Outward show of surrender is not useful. Only what is inside counts.