What fitness routine to follow for a newbie?

Hi all, I’m 29, F. I am super confused on how to start on my fitness journey.

• My objectives are building core strength, stamina and cardio health. • I have done Ashtanga yoga in the past for 3-4 years on and off. • I have never been to a gym.

I’m more of a yoga, Pilates person. But I’m trying to build a routine that’s holistic. I started Pilates at home for now and that’s just about it. I’m also looking to learn a sport like swimming. So I’m really confused as to how to really start and with what? Do I need to a holistic trainer? What to do?