If you want a healthier diet, Harvard’s “Healthy Eating Plate” summarize the basics (things that were mentioned before in this post… Eat food (real food, not processed fake fook). Not too much. Mostly plants (whole grains, legumes, vegetables, fruits… I said mostly because there is no problem with eating fish, eggs, milk and the occasional piece of meat, but probably shouldn’t be your main protein source). Escape from salt (and other sources of excessive sodium. I’m talking about your daily diet not electrolytes drinks for sports) and processed sugar, because those things will kill you (hypertension, diabetes, myocardial infraction, heart failure)
If you do a lot of training you will have to consider more carbs and protein than the usual diet and at the proper times.
If you want a healthier lifestyle add to that a minimum of 210 minutes of exercise weekly (probably you already have this covered), don’t smoke, don’t drink alcohol (or very occasionally and never more than 1 or 2 drinks), have a healthy weight (use your preferred standard of measurement… IMC, fat %, etc) and sleep well (sleep hygiene).