LDS leader Russell Nelson turns 100 in a hundred days. Here’s what he wants for his birthday.

Ready. Set. Serve.

President Russell M. Nelson turns an even 100 this September, and he has a small favor to ask.

The oldest president to ever lead The Church of Jesus Christ of Latter-day Saints issued a call Saturday — a hundred days before his birthday — asking the faith’s members to engage in an act of service between now and his centennial.

“One spiritual offering that would brighten my life,” he wrote on social media, “is for each of us to reach out to ‘the one’ in our lives who may be feeling lost or alone.”

The former heart surgeon didn’t name specific examples or types of service. Instead, drawing on the biblical parable of a shepherd seeking out the one “lost sheep” among a flock of 100, he encouraged members to “consider prayerfully: Who do you know who may be discouraged? Who might you need to reconcile with or ask for forgiveness? Has one name been on your mind lately, though you haven’t quite known why?”

Nelson promised that “as you bring these questions to the Lord, he will inspire you to know how you can reach out and lift one who needs help.”

To complete this task, the church leader has given his flock a head start, issuing his invitation exactly 100 days ahead of his Sept. 9 birthday.

If all members faithfully engaged in the project, it would result in more than 17 million acts of service across the globe. Not bad.

But then, Nelson’s presidency has been defined by one of nearly constant activity. Sweeping changes to worship services, an unprecedented number of temples entering the construction pipeline and a steady stream of policy changes big and small — each of these and more have come to define the nonagenarian leader as a mover and shaker in the minds of faithful Latter-day Saints.

There are signs, however, Nelson’s body has been matching his ambition less and less. His presence at the afternoon Saturday session of the faith’s April General Conference marked the first time in a year that the leader had appeared in person for a portion of the biannual worldwide broadcast.

Later that month, however, he surprised members in Manti, where he led the rededication of the city’s historic pioneer-era temple.

Nelson and his counselors — apostles Dallin Oaks and Henry Eyring, both of whom are 91 — comprise the oldest First Presidency in Latter-day Saint history.

Oaks, a former lawyer and longtime friend of Nelson, is next in line to lead the global church.