- NEW: Nik Wallenda appears calm, focused as he starts historic attempt
- "It's been a dream of mine for a long time," he tells CNN
- Wallenda had a near fall after stumbling on a tightrope above Baltimore's Inner Harbor
- His great-grandfather was killed at the age of 73 attempting to walk between two buildings
(CNN) -- Cloaked in darkness and enveloped by mist, aerialist Nik Wallenda began his daring walk across Niagara Falls on a tightrope late Friday.
It's a historic attempt that observers say is in line with his appetite for the extreme and the high-wire customs of his "Flying Wallendas" family.
"It's been a dream of mine for a long time," Wallenda told CNN. "I'm one of those people who always tries to overachieve. I want to do more. I want to do bigger things."
Wearing a red and black rain jacket and a balance pole around his neck, Wallenda waved to the crowd. He appeared calm and focused as he began the walk.
He took small steps, gingerly placing one foot in front of the other.
Thousands were on hand to watch Wallenda teeter his way on the 2-inch-wide wire over Horseshoe Falls toward Canada. He wore a harness at the insistence of those sponsoring the event, officials say, despite what he said was his desire to walk without a safety rig.
"Fear is debilitating," Wallenda said. "It makes it so it's almost impossible. You overreact and that will cause you to fall."
Wallenda, who hails from multiple generations of high-flying daredevils, had a near fall as he stumbled on a tightrope above Baltimore's Inner Harbor earlier this year.
His great-grandfather Karl Wallenda was killed at the age of 73 attempting to walk between two buildings in Puerto Rico in 1978.
Friday's event is being broadcast on ABC.
CNN's Jason Carroll contributed to this report