Luke Bryan Finds His Purpose Through His Years of Family Loss: 'We're Not Promised Another Day'

Ask Luke Bryan to assess this phase of his career, and he doesn't puff up over his awards or ticket sales or chart positions. Instead, he heads straight to where you think he'd least want to go.

"If this right here" — he motions to the voice that has entertained millions — "quit working in the morning, if I couldn't sing again," he tells PEOPLE, "then I am so blessed by what I've been able to achieve."

It's a powerful expression of Bryan's current state of contentment. But it's also a sobering reminder of what the 45-year-old superstar knows all too well: What he cherishes the most can be taken away in an instant.

As the cover story of the new issue of PEOPLE describes, Bryan has endured a series of unthinkable tragedies over the past 25 years. In 1996, his older brother, Chris, was killed in a car accident at age 26. In 2007, his older sister, Kelly, 39, died suddenly of natural causes that are still unexplained. Seven years later, her husband, Lee, 46, succumbed to a heart attack, leaving behind three children, including a 12-year-old son that Bryan and his wife, Caroline, have since raised.

For more on Luke Bryan's PEOPLE cover story and other top stories, listen to our daily podcast PEOPLE Every Day.

"I've had so many tragedies in my life," says Bryan, "it's almost like you don't want to tell the story because you don't want to feel like you're out there craving sympathy."

Watch the full episode of People Cover Story: Luke Bryan on PeopleTV.com or on the PeopleTV app.

Yet Bryan has never let tragedy defeat him, a conviction that pervades a new docu-series about the singer's life, Luke Bryan: My Dirt Road Diary. All five episodes are available exclusively on IMDb TV, Amazon's premium free streaming service, starting Aug. 6. Through archival footage and interviews, the series traces the contours of Bryan's life and career, from his Leesburg, Georgia, roots to his Nashville heights. It also underscores the profound impact that loss has had on Bryan's life.

"You truly never get over it," he tells PEOPLE. "You truly never settle in your mind that it's happened. I mean, it's always there."

Somehow, though, Bryan has forged a sense of purpose out of his grief. A natural entertainer since his days playing bars in small-town Georgia, he performs today with a passion to lift the spirits of people who may be hurting. By now, he knows that can be pretty much anybody.

"If I can inspire people to move on from tragedy, hopefully by my behavior," he says, "that's what life's all about for me."

Bryan acknowledges he was born on the sunny side — "thank God I've always been a pretty joyful person" — but he's had to deliberately bend toward the light to see his way through the tragedies. He says he still feels a deep connection to his brother, sister and brother-in-law, believing that he has three guardian angels. "Maybe Chris and Kelly and Lee have moved some puzzle pieces around to make my life so fortunate," he says. "When I say my prayers at night, I have to say, 'Thank y'all for looking after us down here.'"

That gratitude, far more than grief, defines Bryan, and he holds tight to what he treasures most, knowing — whether it's voice or his life — "we're not promised another day." His blessings, he also knows, already overflow. Indeed, at this point in his history-making career, he says he has nothing left to prove.

"It's a really special place I'm in, because I don't really feel I need to go reinvent something to complete my life as a country singer," he says. "I've done everything I've ever wanted to do in music."

So anything from here on out really is just gravy?

"Totally," Bryan affirms. "Complete gravy for me. I mean, my true focus is to continue to work hard and write great songs. I may try to chase down a little thing to show them, hey, don't forget I can do that. So I could get real creative within country music. But I'm about getting on stage, making music for the fans and really being content with that."

RELATED VIDEO: Luke Bryan on His Country Music Career

No doubt much of that contentment is due to the fact that Bryan says he finally feels fully confident in his ability to hold the spotlight.

"I'm truly having more fun on stage right now than I ever have, because I know I can do it," he says. "The first three years of headlining, you don't know if you can do it. You have to go prove to yourself that you can do it, and that's very challenging, and it's a lot of pressure. All of that pressure affects your ability to be your best. Now, the lack of pressure can truly make me my best. I get to enjoy and be totally comfortable in the moment — and being totally comfortable allows my personality to come out, which is what people truly want to see."

Of course, he knows well that show of personality includes his signature hips swivels. In a 2014 interview, he swore he'd be ready to hang up his suggestive moves in another 10 years — but now just three years away from that deadline, Bryan is eager to go back on his promise.

"It will always be a fun thing for me to do," he vows. "Me up there dancing and shaking and cutting up — it takes the whole vibe of the concert up. If I can get up there and do it and have fun with myself, so can you."

Bringing the joy is, after all, at the heart of why Luke Bryan entertains.

"The most fun moment," he says, "is when you got this good ol' boy out there in the crowd, and then I get him loosened up and he can go dance with his girl. And she's like, 'Well, I've never seen him dance and have fun like that.' That's what I want. I just want to bring smiles to people."

When he reaches the end of his days, Bryan says, he's not going to measure his career by counting his many awards or his No. 1s (now 26 — and counting).

"I'm going to look back at what people were doing when I was onstage and singing to them," he says, flashing his familiar grin. "They were having a blast — the time of their life!"

For more from Luke Bryan, pick up the latest issue of PEOPLE, on newsstands everywhere Friday.