Solitude. Then, I'd say acceptance from friends/family, followed by a good routine.

I've tried learning alone, but after 6 - 12 months it becomes really difficult. Being around a self-learning community daily makes a world of difference, I'm about to start my fourth year and I'm loving it.

Being part of a program also reduces societal pressure. Any program really, just to be able to give a simple answer when people ask you what you are doing. Otherwise, it's easy to be met with doubt and cynical questions.

Lastly routine, I see self-learning as a day job. You want to clock N hours per day and don't spend any time procrastinating. I've been building habits for 5-10 years, and I'm reaching a point where I can be productive, but it takes time and patience.