Former Mayor Bob Walkup was taken to Saint Mary's hospital Saturday afternoon suffering from dehydration.
The 75 year old Walkup was on an early morning bike ride with friends when be began to cramp up and feel uneasy.
"I could sense my body was shutting down," he says.
His legs were cramping about 15 miles into a 30 mile bike ride on the new section of the Riverwalk and it became apparent he could not finish.
He made it back to his car at Campbell near the River, drank some water and ate a banana, then drove home.
But once home, the symptoms continued.
"I had a tightness in my chest and my leg muscles were cramping," he says. He told his wife Beth, "call an ambulance, this isn't right."
Within two and a half minutes, paramedics arrived and treated him at his house before transporting him to St. Mary's where he stayed until Monday morning.
Walkup admits he was not prepared.
He had walked nine holes of golf the afternoon before and did not rehydrate himself before heading out on the bike ride.
"I should have known better," he says. "It happens very quickly."
He says there "were no early warning signs."
Dehydration is a common problem in Tucson during the summer months.
Two tourists have died in Tucson in the past week during the current heat wave.
Many Tucson residents, including those who have lived here for many years, have stories about close calls in the summer sun.
Rehydrating every morning by either eating breakfast or drinking thirst aides, is a good idea this time of year, especially before participating in outdoor activities.
"Morning is when you are most dehydrated," says Dr. Rebecca Winfield, from TMC. "You've been asleep for six to eight hours."
She says people need to be aware of the symptoms.
"That includes muscle cramping, a little nausea, maybe even some confusion," she says. "That's pretty typical of mild dehydration."
Age is another factor.
As people grow older, they become less sensitive to thirst.
"I've got to be smart," says Walkup. "I can't play the invincible game."
Walkup is in good physical condition, often biking 30 to 40 miles in a day. He also walks nearly every day.
But he says this was a wake up call and he needs to rethink things.