Eat a balanced diet, drink lots of water and get out and exercise. Whether its poodles, people or parakeets, proper health care is in many ways, universal.
All living things fall prey to a wide assortment of health issues, caused by Obesity, Improper Diet and lacking of any kind of meaningful exercise.
So if you or your dog, love junk food, and spend most of your time on the couch, It really should not come as any surprise to you, that either of you could be on your way to Heart Disease, Joint Problems, Diabetes, or any of a dozen other physical and emotional problems.
But, by the same token, if you eat right and get off your butt to exercise, you get to enjoy the benefits of better health, as a happier more and energetic person.
There is not a single most important thing, to acquire and maintain a healthy life. But without question somewhere up there in the top, is drinking plenty of water.
For your dog, there should always be a water bowl available, full of good clean water. That means that you did a thorough search within your municipality, to determine, that the water quality is sound. If you have any doubt or question, there is always bottled water or buy yourself a filter.
In people and in puppies (dogs) to maintain a quality healthy lifestyle is to eat a nutritious and balanced diet. Both you and your dog should avoid processed foods, laced with preservatives, fillers and additives. What every organism needs is to eat foods, that provide (in the proper quantities) all the vitamins, minerals and proteins, according to the requirements necessary for them as a species. Of course it should go without saying, that providing your dog with Table Scraps or Junk food it out of the question.
Now that you both are, eating the right foods, & drinking plenty of water. Your last task is the most difficult for most, getting enough exercise, there is little to be said on this except DO IT, but remember if you and Fido have not had any meaningful exercise, since the Carter Administration, you better see both your Doctors to get clearance, before you start.