Unfortunately by the time we get to the point in our lives where we can purchase the better cameras, and great lens we have reached our prime. A 20 year old usually cannot afford a digital SLR unless he is a professional photographer or has a great job with lots of disposable income. The downside of this is that when we are in our prime our enthusiasm and finances are in line but our bodies are not. The best camera and best lens combo placed onto a rock solid tripod will not give us the stunning photo of a waterfall that we all want if we cannot physically get to the location without a major cardiac event. Our hand held shots (and we all take them) also will look poor.
With a little regular exercise our trips to the locations will be more enjoyable and our time onsite will be more pleasant without gasping for air. And we will not entertain any thoughts of tossing the tripod to save us the lug out.
A training program need not lead to marathons or triathlons. Just better everyday living and steadier hands. Slower heart rate is a byproduct of exercise and the slower the heart the steadier the hands. Start by walking 10 min a day; everyday is better than 20 min twice a week because you are sore after each trip out. Consistency is the answer. As you feel that the walk is no longer challenging you can add time or speed. Always do just a little too little. You can always go faster or longer tomorrow but if you do too much today tomorrow will be a write-off. There are great sites to help you with your training just Google run, walk, or training. While you are training remember these are great stock photo opportunities!
Remember we want grow as a photographer in a technical and artistic sense not in a physical girth sense.