I'll respond to your question about your talk (Dad sent him an email asking about his experience in preparing for his mission and if there was anything he would have done differently) and hopefully I'll be able to read and answer your email about the witness.
I guess as I look back on the decisions I made leading up to the mission and what I now realize is that Elder cook is 100% right (Elder Cook reference below). In the end, school and work and other things like sports don't matter at all in this day and age. The most important thing that people should focus on is learning and living the gospel because that is where true joy and happiness lie. I guess my advice would be to focus on God and His church with all your energy and the other things will fall into place. It is not bad to do sports and hang with friends, but there is definitely more that would be worthwhile (i.e., the need to prioritize - refer to Elder Oak's talk "Good, Better, Best" --> Good, Better, Best ). I was not as behind as the young man in the story, but I was not to the level that is expected of the Lord.
I guess the only way to encourage this type of learning is to have the leaders stress the importance of gaining that conversion. I'm sorry - it probably isn't much to work with: - ), but maybe a start.
Paragraph from Elder Cook:
Elder Quentin L. Cook's Oct 2014 General Conference talk "Choose Wisely" - https://www.lds.org/general-conference/2014/10/choose-wisely?lang=eng. Particularly this passage:
"I recently met a fine teenage young man. His goals were to go on a mission, obtain an education, marry in the temple, and have a faithful happy family. I was very pleased with his goals. But during further conversation, it became evident that his conduct and the choices he was making were not consistent with his goals. I felt he genuinely wanted to go on a mission and was avoiding serious transgressions that would prohibit a mission, but his day-to-day conduct was not preparing him for the physical, emotional, social, intellectual, and spiritual challenges he would face.7 He had not learned to work hard. He was not serious about school or seminary. He attended church, but he had not read the Book of Mormon. He was spending a large amount of time on video games and social media. He seemed to think that showing up for his mission would be sufficient. Young men, please recommit to worthy conduct and serious preparation to be emissaries of our Lord and Savior, Jesus Christ."