There are a lot more things to check/do besides "eating healthy, workout and not having apnea".

For example, the times when you eat matter (even if you eat healthy to begin with). The light levels matter - is your bedroom pitch dark? Noise levels matter. Temperatures matter a lot. Things like sleep position could play a role. Pets sleeping with you waking you up at night. And several other things besides.

Or you might have a condition that prevents you from sleeping well, even if it's not apnea. Might be stress. Or something that needs medical treatment, or a vitamin deficiency. You might also need supplements such as melatonin.

You could try different combinations of beds, pillows, blankets, white noise, blackout curtains-- there are lots of different ways to adjust your sleep environment to do a bit of trial-and-error to find out what helps.

I found that I sleep best with blackout, loud white noise, a very soft pillow under my head, and a firm pillow beside my legs so I can sleep on my back with one leg bent and resting on the leg pillow. The bent leg thing is not something I've ever heard of anyone else doing. I just had to figure it out by trying a ton of different ways of arranging my limbs in bed-- previously I had really struggled with hip pain during the night no matter how I slept.

also ambient temperature, etc.

and sunlight during the day, darkness during the night (or filtering out blue light with glasses / apps)

There are professionals (medical staff) that specialize in this stuff.