This song here is dedicated to Danny Dan and may he rest in peace
Who at his funeral left us with the words that
He did it his way,

from Jay Z – In My Lifetime Lyrics on Rap Genius

Meaning

From a 1998 Vibe article in which Jay is uncharacteristically candid:

“Danny Dan was a cat in the [Marcy] projects, coming up,” says Jay. “He was very influential in my life, but from afar. Holmes was doing it. He’d always put something away, not touch it. I was like, I need to be doing that."
Danny Dan was five years older than Jay and was known for being the kind of reckless driver who would push German sedans past 100 mph down New York’s crowded streets. "He always said he’d die in a car crash, and he did,” say Jay. “Coming back from D.C. on I-95."
Those that talk say Danny’s death left a vacancy [in the drug industry], further south, in Virginia and that Jay moved on it, opened it up further, and creamed off.

In the movie The Danny Diamonds Story: The Don of Marcy, Danny’s brother David recounts how Jay rapped for Danny one time and Danny gave him money and told him to make a record. David thinks Jay instead just invested this money in the drug game. But Jay has of course implied he used his profits from the drug trade to finance his rap career.

http://www.youtube.com/watch?v=155dQPzMa5g&feature=player_detailpage#t=6m37s

To help improve the meaning of these lyrics, visit “In My Lifetime” by Jay Z Lyrics and leave a comment on the lyrics box