Life is actually very simple, and all other concepts can be covered in one simple concept...balance. The world's cycles and the universe acts in a stasis or balance. It is maintaining this balance that sometimes seems to be a bit difficult. None-the-less, it is this very simple idea that can make the difference between, "doing it tough" and "having it easy."
This concept of balance applies to all organisms in the universe as well as inorganic matter. Everything has a balanced state. When this is shifted is when "life" appears to be difficult. In nature, this balance is restored often through violent means. An overabundance of an organisms prey leads to population increase, a decline in the prey means the organisms starve to death until an equilibrium between predator and prey is restored...and so on.
Human beings are not exempt from the concept although at times it seems that we are the only ones who willfully ignore balance. An overindulgence in rich foods, leads to digestive upset. A lack of balance between caffeine intake and water intake leads to health issues and dependence etc. The list of imbalances we perpetrate on ourselves is endless, most of which we actually do to ourselves.
When life seems to be complicated or difficult, it might pay to look at the things that may be out of balance. For example are the sleep/rest hours in balance with your hard work hours? Are your times at play in balance with your times at work? Are the foods you eat increasing or decreasing the balance one way or another?
Basically, it is the lack of balance that leads to the perception that you are tired, run down, out of energy, cranky, etc. It is your bodies way of letting you know that something is not quite right in terms of your overall well being. A lot of damage both physically and emotionally can be caused if an imbalance is not restored to equilibrium within a short period of time.
Identify the areas you are experiencing imbalance (typically this will be related to nourishment or time spent working vs playing), then actively take control of the situation in order to restore the balance.
This could involve seeking outside help, divine help, medical professionals or friends. Don't let anything stop you...seek balance. Life gets so much easier then...smile