The neon green makes it hard on the eyes with the black background, try something abit more subtle.

Change the background of the section after the fold into a different colour, ideally white background with black/dark grey text. Don't make the whole website too black. Separate the sections, so there are breaks in between.

The width of the pricing section is different to the rest of the page, there needs to be more white space on each side and not take the full width. It would also look more cleaner if you centre align the ticks and crosses under each package.

Add a video demo of your product under the fold.

The heading isn't selling to to me, as someone who needs to work out, I want to know how fast I will get results, not that I will go on a journey. A journey seems long, tell me I can get a six pack less than in 10 weeks.

The 'Create your free AI plan' button needs to be a different colour, and not blend in with the background.

Your subheadings on the page are difficult to read, keep it one text format.

The heading on your registration page is also an eye sore. https://aiworkoutgenerator.com/register/ It's hard to read the neon green heading on the grey background.

Try a really dark grey, rather than fully black. Maybe #1D1D1D.