Dr. James Dobson is saying his final farewell to the ministry he founded 33 years ago.

His last day at Focus on the Family is Friday.

"Nothing is forever. Everything has a shelf life," Dobson said in one of his final radio broadcasts at the Colorado Springs-based organization.

Some 40,000 cards expressing gratitude and appreciation have poured in for the evangelical leader who has spent three fourths of his professional life helping people build healthy families. Calls from listeners around the world were featured this week on the ministry's daily broadcast, each sharing how much Dobson has influenced their lives.

For Dobson, 73, both sadness and a conviction that "this is right" are the two emotions "going on inside" of him, he said Friday.

Though this week marks the final days of transition – a period that began some 10 years ago – at Focus on the Family, Dobson will not be signing off the air just yet.

He has a new ministry called "Family Talk" that he'll be starting "not very far" from Focus on the Family. With a $1 million grant from FOTF, Dobson plans to continue to reach families, addressing marriage, parenting and cultural issues, with his son, Ryan, alongside him.

Family Talk, Dobson stressed, is not meant to compete with Focus on the Family, which reaches more than 220 million people. But with "moral issues getting more discouraging" and the family unit continuing to disintegrate, the need for family ministry is great, he noted.

"How silly to think one organization is going to meet the need of the whole country," he said, noting that one church on the corner can't reach an entire city either. "There's plenty of work for all of us to do."

"I'm not setting out to construct some magnificent organization like, frankly, this one is. But I also do not believe the Lord is through using my voice in the culture and speaking to parents," he highlighted.

Denouncing several media reports that have painted Dobson's new endeavor as competition, the evangelical leader said, "It's bologna! Don't believe it."

"It just bugs me like crazy that the media is out there saying the reason I'm doing this is to create a ministry for my son or [that it's] some kind of hostile act against Focus on the Family," he said.

"I'm not going into this for any personal gain. I'm not going to take a salary just like I haven't here," he added.

"To be honest with you at my age in life every now and then I say 'what are you doing here?' ... And there are other times where I'm keenly aware that this is what the Lord has asked me to do."

After launching Focus on the Family from a two-room office in Arcadia, Calif., in 1977, Dobson has grown the ministry to an influential organization, reaching more than 220 million people around the world. Talks of leadership transition began some 10 years ago when Dobson and his wife, Shirley, began praying about it.

One of the common errors of founders and CEOs, he said, is to hold on to the reigns too long and subsequently stifle the growth and creativity of the organization. Convinced that the Lord was telling him to let go, Dobson has for the past several years stepped down from leadership positions, including his role as president and CEO in 2003 and chairman of the ministry in 2009.

Pat Caruana, chairman of the Focus on the Family board, expressed his thanks as he came to realize the wisdom of Dobson's decision to begin the transition so early on.

"As we come to this point, I have grown greatly to appreciate the wisdom and the courage that it took for you to initiate that discussion (about transition) so early on so that we can come today and conclude this in a way that honors God and that respects all that you and Shirley have done for this ministry," he said.

After carrying the baton for three decades, Dobson has come to the end of his lap in the relay race and is now handing it off, as he illustrated. As long as that baton is transferred successfully – that is, getting it snuggly in the hands of current president Jim Daly with the same values and same commitment to the Lord – then the ministry can continue for many years, Dobson said.