Since the next occurrence of this phenomenon will be in 2117, unless there are fantastic medical advances and you’re very young, this will be your only chance to see this.
In about 10 minutes from now (ca 6 p.m. EST in the US), the transit of Venus across the sun will begin as seen from the observatory at Mauna Kea in Hawaii. The webcast, though, has already started (there are commentaries and interviews), so go here—and have fun.
Here’s a screenshot as the planet moves into the Sun at upper right:
A closer view from the Mount Wilson Observatory in California: