The Paisley side froze in the early stages and were lucky only to be trailing by Ryan Stevenson's 10th-minute opener before Esmael Goncalves scored out of the blue in the 37th minute to take the teams into the interval level.
The Buddies boss set about his players at the break and they responded magnificently.
Steven Thompson converted a Paul Dummett cross a minute into the second-half before Conor Newton drove in number three and although Stevenson reduced the deficit with six minutes remaining to ensure a nervy ending, the Paisley side held out to win the club's first major trophy since 1987.
Asked whether at the interval he gave the team talk of his life, Lennon had no doubt.
"Yes. I got into the players at half-time and reminded them that if they wanted to become legends there was a game of football to be played," he said.
"Our problem in the first-half was that we didn't pass the ball.
"Hearts came out the traps well, they were one-up, they had the better opportunities and probably the only opportunity we had, we took it.
"That would have deflated them a little bit and gave us a lift but it was not the lift that got us started, that came when we got them in at the break.
"There was a little bit of emotion, there were raised voices, some comforting words but more importantly, I reminded them that these opportunities don't come very often.
"Some players will play their full career and never get the opportunity to play in a national final in the national stadium.
"And the reality is that for some of these players it might be their last, so my message to them was make sure that it was a day that they could remember for the rest of their lives and to be fair they gave us and everyone associated with our wonderful football club a memory to cherish for the rest of our lives."