Most hosting companies (ie godaddy) have easy to use website builders but they aren’t very good if you need anything beyond static pages.
If you are looking for more advanced features you may want to use wordpress (free but you still need hosting).
Assuming you are a trainer, you may want some advanced features to train online or book appointments. Your best bet is to look at some premade templates which are built with wordpress. Check out www.fitprosites.com or www.trainertry.com. Both offer the advanced features and include hosting. I went with trainertry and it’s been great for my exposure online.