Online training hints

Hi folks, I've been an personal trainer for about ~5 years...

Few months ago I got to an idea to work as an online PT mainly because I don't have time to scale anymore like this. I've recently talked to a lot of clients and they want to work with me online... but the deal is that I really don't have any clue what systems to use 😅. Google spreadsheet or any kind of fitness app was first on my mind... I would appreaciate any kind of hints.

If you are willing to share ofc. Ty ❤️