A method of operating a wind turbine comprising: determining an operational time of at least one wind turbine component comprising load obtaining periods; determining a reference accumulated fatigue at the operational time of at least one wind turbine component comprising: determining a reference accumulated fatigue at design lifetime and determining a reference accumulated fatigue trend line or curve; obtaining a partial load indicator from the at least one wind turbine component for each of the load obtaining periods comprising: obtaining a wind speed; obtaining a turbulence intensity; and calculating loads on the at least one wind turbine component during a load obtaining period based at least on the wind speed and the turbulence intensity; determining a real accumulated fatigue in the at least one wind turbine component comprising obtaining an accumulated load indicator by adding the partial load indicators of each of the load obtaining periods and determining an equivalent fatigue load based at least on the obtained partial load indicator from the at least one wind turbine component; determining a trend line or curve of the real accumulated fatigue; comparing the real accumulated fatigue and the reference accumulated fatigue at the operational time; determining a first inclination of the reference accumulated fatigue trend line or curve at the operational time determining a second inclination of the real accumulated fatigue trend line or curve at the operational time, comparing the first and second inclinations; and controlling the operation of the wind turbine based at least on a result of comparing the real accumulated fatigue and the reference accumulated fatigue and on a result of the comparing of the first and second inclinations. determining an operational time of at least one wind turbine component comprising load obtaining periods; determining a reference accumulated fatigue at the operational time of at least one wind turbine component comprising: determining a reference accumulated fatigue at design lifetime and determining a reference accumulated fatigue trend line or curve; obtaining a partial load indicator from the at least one wind turbine component for each of the load obtaining periods comprising: obtaining a wind speed; obtaining a turbulence intensity; and calculating loads on the at least one wind turbine component during a load obtaining period based at least on the wind speed and the turbulence intensity; obtaining a wind speed; obtaining a turbulence intensity; and calculating loads on the at least one wind turbine component during a load obtaining period based at least on the wind speed and the turbulence intensity; determining a real accumulated fatigue in the at least one wind turbine component comprising obtaining an accumulated load indicator by adding the partial load indicators of each of the load obtaining periods and determining an equivalent fatigue load based at least on the obtained partial load indicator from the at least one wind turbine component; determining a trend line or curve of the real accumulated fatigue; comparing the real accumulated fatigue and the reference accumulated fatigue at the operational time; determining a first inclination of the reference accumulated fatigue trend line or curve at the operational time determining a second inclination of the real accumulated fatigue trend line or curve at the operational time, comparing the first and second inclinations; and controlling the operation of the wind turbine based at least on a result of comparing the real accumulated fatigue and the reference accumulated fatigue and on a result of the comparing of the first and second inclinations.