Here's a typical approach to growing a community in which members participate.
None of these ideas will be new to you.
1) Ask your members to share their best advice, funniest story, biggest challenge, or anything else that is the 'best, most' or definitive response to the question. This drives activity from existing members.
2) Publish this as an eBook. Each members gets their own page. Every page links back to both the member profile to ask for more information and a link to a relevant discussion within the community. This can be as big as you like it to be. You can also sell sponsorship in it to other companies if you like.
3) Create easy 'share this' links. Which will send already completed tweets directly to the target audience. Everyone that reads it is invited to share it.
4) Create a specific page for general links. People that click general links in the community go to a page designed specifically for them. On this page it welcomes newcomers and asks them to share their funniest/best stories for a second edition of the book. Ensure these answers are posted directly to a discussion thread.
5) Give feedback on each participant's story and ask for further information. Drop each participate a message about their story and ask for further information/profile pictures/details about them on their profile for the book too.
6) Host an event where people can share/discuss their stories. Use GoToWebinar if you like. Mute and unmute people at will. Let as many of your members as possible share their stories and talk with one another. Record this and send it out to all members (with a link to share it).
7) Rate the stories. Have a poll where everyone can rate their stories to determine the order of the book. Invite members to share their stories to get more people to vote for them.
8) Ask for the opposite. Now ask for the opposite. Ask for their biggest mistakes, their worst moments etc…This is purely for a fun outtakes book.
If you've done the steps above correctly, you'll have a big batch of new members who have made several contributions in the community without even realizing it's becoming a habit.
This group of members know each other, they've participated in live events, they feel a part of the community. All of the above is without introduction threads, pestering people to participate, and it uses existing motivations.
You can make the process of joining and becoming a regular participant in the community as fun as it can be.