Hammer's involvement stretches back not just years, but decades as the disease has touched him from an early age.
"My Mom died on Christmas Day of cancer when I was 9," he explained. "She was sick by the time I was 4 or 5 so the earliest I can remember is her being sick. That never leaves you."
Twenty years later, married to wife Kim and with a child on the way, Hammer discovered a small lump on one of his testicles.
"I was in the shower and I felt this thing, just the size of a small pebble. But I went to the doctor to get it checked out," he said.
Doctors confirmed that it was the early stage of testicular cancer and within days Hammer had surgery to have the testicle removed. Follow-up tests were run within six months to see if any cells had come back but it appeared that he had caught it in time.
The following December though, Hammer began to experience back pain. He said he didn't attribute it to cancer since his last checkup didn't show any signs. "I was coaching track, I was playing softball three nights a week. I had a clean bill of health."
A week before Christmas, he collapsed and was having difficulty breathing. An examination showed that the cancer had returned and spread into his chest cavity. He was placed on an extremely rigorous regimen of chemotherapy.
"I went in five days in a row for six hours. And then I'd have two weeks to recover," he explained.
The 26 rounds of treatment lasted until April, leaving the athletic 30-year-old weakened and sick.
"Our daughter Shayna was a year old then," Hammer said. "So for a few months there, Kim was taking care of two kids because I was pretty much useless."
Kim Hammer said that having Shayna was a godsend in keeping Bob fighting to make it through his chemo. "She was the light at the end of a long tunnel that he needed to keep going."
Doctors told Hammer not to get close to the 13-month-old while he was undergoing chemo because of risk of germs and infection from the toddler."We both decided that what is the point of living or fighting to live if you can't even be with the ones that mean the most to you," Kim recalled. "He spent every waking moment with her- runny nose, sticky hands and all- and I truly believe her love and his love for her is what got him through the thick of it."
It was during this time that Hammer also found himself on the path to making a difference in the lives of others suffering from the disease. A friend had given him Lance Armstrong's book about his similar battle with cancer. This gave Hammer the motivation to be a part of the cycling star's annual "Ride for the Roses" in Texas.
Still convalescing, Hammer set to work making phone calls and asking for donations and managed to raise $15,000 for the Lance Armstrong Foundation. That set him in motion for the next stage of his life.
"Raising over $10,000 put us in an elite group that would get to meet Lance," recalled Hammer.
The day after his final chemotherapy session, Hammer and his wife Kim flew to Texas to meet Armstrong.
"I'm 30, bald, ghost pale white and a day out of treatment. The rest of these guys are all corporate guys who paid their $10,000 to meet Lance. Kim and I stood out like a sore thumb," he said with a laugh.
Others at the event took the Hammers and introduced them to Armstrong and to the cyclist's oncologist, Dr. Craig Nichols. This chance meeting would change the Hammer family's lives.
"The masses in my chest and back had shrunk and I was scheduled for surgery at Stanford," said Hammer. "The surgery would have prevented me from ever having any more children."
Hammer told Nichols his story, and the doctor replied that perhaps it wasn't necessary to have the surgery after all.
"It was his opinion that the masses were scar tissue," remembered Hammer. "That Monday I faxed him my medical records, and that night he called my doctor and told him I didn't need the surgery."
Hammer followed Nichols' advice and chose not to have the surgery. "A little over a year later we conceived Josh (now 5) naturally. Which in and of itself is rare in testicular cancer cases. Long story short, my son is here today because of the Lance Armstrong Foundation," he said.
Hammer remained active in fundraising for the foundation but continued to look for "the big thing," the event that would really make a difference. After taking over the reins of his company's annual corporate golf outing, he knew he'd found a winner. He set about creating the Have a Ball Testicular Cancer Foundation plus started working on the first Have a Ball golf outing.
To get the wheels rolling he spoke with Steven Seaweed, a disc jockey for 107.7 "The Bone." Having the station willing to help promote the fledgling event gave Hammer a needed in with corporate sponsors and the tournament grew from there.
"In our first year I hoped to raise $25,000," said Hammer. "I raised $50,000." Of that, $35,000 went to the foundation and the rest was spread among other charities. Since then the amounts have increased until last year when it raised $195,000. Hammer said even with the economy down he's expecting to still pull in around $150,000 in the July 17 event.
At the same time the tournament went from having 80 sponsors involved to more than 200, including Ariba, AMGEN, UPS, Genentech and United Airlines.
The last two years Have a Ball has been the winner of the annual "Live Strong Challenge," and last year was No. 2 in the world for donations to the Armstrong Foundation. Hammer added, "And we only donated half our funds to them."
The group also helped out 15 different charities, and each day they hear from other entities that need financial assistance. Hammer said his plan is to keep helping as much as he can.
"It just doesn't end, because there's so many people affected by cancer," he said. "It's just stems of a tree that keeps growing and growing."
As the event grows in popularity, so does talk of branching it out to other venues. Hammer said he's had discussions with the Lance Armstrong Foundation to hold the Have a Ball tournaments in other states, to help raise funds and raise awareness of testicular cancer.
Hammer seems amazed by it all.
"I'm just a guy from Danville," he said. "I'm just trying to give back a little bit and it just got bigger than we anticipated."
Charities that benefit from the Have a Ball Foundation
Children's Hospital and Research Center Oakland
Sean Kemmerling Testicular Cancer Foundation
Susan G. Komen - For the Cure
Wellness Community of Silicon Valley
Leukemia and Lymphoma Society
Ulman Cancer Fund for Young Adults
American Cancer Society Relay for Life
UCSF Cancer Resource Center
The Second Opinion