Now before I dive in, always check with your doctor before making drastic changes, because there are a handful of situations where you do need to be careful, whether it be high blood pressure or another medical issue, or perhaps a medication you may be on, but in healthy adults reducing your sodium intake will actually make your athletic performance suffer as well as make you feel MORE tired and lethargic.
Sodium and potassium are REQUIRED for all bodily functions. Your nerves use sodium and potassium to regulate sending signals all over your body. This includes everything from to your brain for normal cognitive function, to your muscles to be able to contract during exercise. If your electrolyte levels fall too low, your body will literally stop being able to send signals. What happens when your car is running out of gas? Its start puttering until it eventually stops completely. This is the basis behind Gatorade and other recovery supplements, by combining salt, potassium, and usually magnesium and calcium with carbs, you are able to more efficiently replace any low stores and keep them at a more optimal level and stay hydrated. There are some top level athletes that will consume as much as 10g of sodium a day (not recommended for everyone).
Now I understand not everyone is training for optimal performance, possibly not training at all, but those same optimal levels are required for all bodily function. You could start having heart palpitations, severe muscle cramping and severe lack of strength and energy. Having sodium levels that are too low could actually negatively impact your total cholesterol to HDL levels, which could increase your risk for heart disease. Even worse, salt deficiency increases your chances of developing insulin resistance. The stigma that salt makes you gain weight and cutting it out makes you lose weight is not understood well. While some people will retain a noticeable amount of water if they consume more than normal, this is generally because they are not taking adequate levels in the first place and your body rebounds with extra water. If you try to consume a relatively consistent amount on a daily basis, you will see your body weight levels out quickly and you will feel better on a daily basis. Remember, our bodies like being in homeostasis.
A very easy way to stay healthy and not overthink things is to eat a variety of fruits an vegetables, and use pink Himalayan sea salt when you are cooking. Himalayan salt is a much better quality source of sodium over regular table salt, and is full of trace minerals too.