Set achievable goals by choosing your struggle.
Pain and struggle is an unavoidable part of the road to success. In fact, those that achieve success love the challenge. Those who enjoy the challenge of a gym workout are ones who run marathons; just like those who enjoy working late and dealing with corporate politics, are the ones who climb up that ladder, etc.
The reward of success will be well worth the struggle, but the joy will be in the climb itself. When you find a goal that you will happily and actively work towards, you have found a goal you will achieve successfully.