1.The journey to becoming healthy is endless. (is it natural?) endless means "it will never end" and has a negative connotation. This book is SO boring and LONG. It's just endless! I would say, "the journey to good health is a lifelong one" or "the journey to good health is ongoing" 2. We are dedicated to present you the best water. or We are dedicated to presenting you the best water. (which one is right?) dedicated to v+ing 3. The purpose is ultimately health or The purpose is ultimated staying healthy (which one is better)? The first one is better, but since you don't provide context (the purpose of WHAT?) it is difficult to suggest alternatives that sound more natural.