Personal as in "I'd rather not go into details about it" because it would be unwise for any of us to share certain things that can be used against us.
Forgive me. I did not quite understand your sentence in its entirety. "Since I can remember Beltane was the start of the new year for personal reasons"
Do you mean that since you've been here, on JoS/ToZ, Beltane is considered the beginning of the year? And by “for personal reasons,” do you mean that High Priestess Pythia chose it for her own personal reasons?