艰辛 (jiān xīn) describes something arduous and marked by hardship, often over a long period. It emphasizes the toil and suffering more than 辛苦 (xīn kǔ, 'tiring, hardworking') and is more about the nature of the experience than 艰苦 (jiān kǔ, 'tough conditions') or 艰难 (jiān nán, 'difficult'). Use 艰辛 for journeys, experiences, efforts that are deeply demanding and grueling.