Not everyone has access to in-person trainers and that's completely understandable (Dr. Carter said she even opted out of personal training sessions herself because she wanted to spend that money on other things)! But, there are ways you can still use their expertise at home. Dr. Carter pointed to YouTube as a great resource to learn about proper form while you're working out, but she cautioned that you should vet your experts. She said you can look for content that's backed by the American Orthopedic Society For Sports Medicine (AOSSM), the American Medical Society For Sports Medicine (AMSSM), or the National Athletic Trainers' Association (NATA).
In addition, finding content on YouTube from a certified personal trainer is ideal, just so you can make sure the workouts you're following are safe and legitimate. A few names on YouTube to start are Heather Robertson, Sydney Cummings, Sugary Six Pack, and BodyFit by Amy. You can also find a wide range of workouts — HIIT, bodyweight, dance, etc. — on POPSUGAR Fitness's YouTube channel.
You can use other resources such as apps that give you access to trainer-led routines, whether they be audio-based, follow-along videos, or lists of exercises with demonstrations attached. For instance, I stream workout classes led by personal trainers at home via my Peloton app (you don't need a Peloton Tread or Peloton Bike). If you have money for it, you can also utilise the virtual personal training feature on the Mirror where you're essentially FaceTiming with a professional in realtime. (And, of course devices like Tonal can guide you through workouts as well, but, as it is for Mirror, you'd need more money than for, let's say, apps you can purchase.)