Diamond Bar High School teacher Christian Calero went from facing death to instructing students on the finer points of public speaking—all in the span of seven months. Despite having gone through a rigorous treatment process to kill the cancer cells residing in his neck, the cancer survivor is back to his teaching ways, spending his days in class pushing his students toward success.

Calero first noticed a large lump on his neck in June 2014, but neglected to say anything about it to his wife until October, at which point he went to visit a doctor. He was then referred to multiple physicians until he had a biopsy performed in early January 2015, in which doctors took a tissue sample from his neck. A few days later, the bad news was delivered to his family.

He went through a rigorous treatment process as part of a clinical trial, which is a study done to help determine the validity of new treatments.

It consisted of one dose of super-chemotherapy, double the dosage of a regular treatment, and five days of radiation per week. Due to side effects of the treatment, Calero was intermittently hospitalized and had trouble eating; he eventually lost 40 pounds and needed a stomach tube and IV drips to stay alive. He also lost the ability to speak for five weeks during his treatment and was confined to a wheelchair.

“The treatment is a thousand times worse than the cancer…[But] I didn’t think I could look at my daughters or my wife and not complete the entire program, because there is no promise you will be cancer-free when you’re done,” he reflected.

According to the Centers for Disease Control and Prevention, cancer claims almost eight million lives annually worldwide. The disease has a death rate of 32%, according to the U.S. Department of Health and Human Services.

The chemicals and particles that bombarded his neck and jaw have left Calero with various lasting side effects; he currently does not produce saliva and has trouble eating. Doctors have told him that it will be at least another year before he will be able to taste anything again.

Despite the changes, Calero, a devout Christian, sees only the bright side of life.

He is extremely grateful for his family and friends’ support during his fight and says that God and prayers from those around him got him through the ordeal.

“Prayer is a very powerful thing, and I had a lot of people praying for me. God does miracles. I’m a very blessed man to have so many people in my life who care about me,” he said.

The main thing Calero has learned from his battle against cancer has been how to organize his priorities.

He has discovered what really matters to him and is now better at managing his life.

“I think what happens is you really get your priorities in order. A lot of times the bottom of your priority list can seem like it’s the most important, and it’s just not really. My priorities are [now] set in stone,” he said.

The history, public speaking, and video development teacher is very open about his experience and wants everyone to know about his success. However, he wasn’t always so willing to share, as it was once very difficult for him to deal with the look of pity he received every time he told someone.

Now, he encourages students to go talk to him in his room if they feel overwhelmed by anything going on in their lives.

“I’ll talk forever about it. I’ll talk about the ugly, bad parts, I’ll talk about the good, glorious parts, because there are a lot of kids out there who are dealing with this.”