In my line of work, I communicate with Spirit Guides every day, but do I still wonder if they are real? Absolutely. Following is a personal story, on the subject, that surprised and amazed me.
My father went to the doctor for a check up. He had a chest x-ray, and got a clean bill of health. A year later he went back, because he was having shoulder pain, that had become increasingly severe and debilitating. Unexpectedly, he was diagnosed with cancer on the lining of his lung, which had eaten away at his ribs, leaving only points of bone. The diagnosis was terminal, with treatment to shrink the size of the tumor, and medication to keep him comfortable. He came home from the appointment, and sat down with my sister, showing her the new x-rays, and what the doctor had said. He told her that his "Spirit Guide, Tony", had spoken to him and told him that he would come and get him, when it was his time to go. This confused my sister, as my father is a strict Catholic, and has never discussed anything of the sort, much less used a term such as "spirit guide". (At that time, my Dad was not on any medication, and did not have any mental disorders. He had been completely healthy, was full of energy and active.)
Soon after, my Dad needed a morphine pump to help him deal with the incredible pain. He lived through nine months of hallucinations, with short spurts of mental clarity, in a bedridden hell. Shortly before his death, he called me on the phone to say, "I don't think I'm going to make it. I think the cancer's getting me." It was a call for me to come home, because he knew he was dying. I didn't make it there to see him before he passed, and I think that will always haunt me with deep regret. A few days later, he became very lucid, and told my sister that "Tony" was here to get him. And then he was gone later that day.