I don’t know of any long-term programs like that for adults (who would have the time/money?), but things you could consider:
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Becoming a scout leader or an adult guide for similar programs. If you don’t like kids, Venturing is for 14-21 year olds
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Joining or starting Meetup.com outdoor groups
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Taking classes at a local REI or rock gym
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Checking your local colleges/universities for outdoor workshops (run as auxiliary programs for all community members, student or not, that usually run for a few days or a few weekends at a time)
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Taking or teaching NOLS classes
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On a vacation, joining a Sierra Club or REI.com outing
These mostly lack the structure of scouting (unless you’re an adult leading a similar group), but they do have the skill-building and meet-new-people aspects. Their primary difference is that they’re far more specialized and targeted towards particular activities, rather than “building character and skills” together.