When pursuing personal goals, individuals may experience fluctuations in goal-related dimensions like commitment and enjoyment. We present an approach to describe, analyze, and explain such within-person variability. In Part I, we determined to which extent within-person variability over time contributes to the total variability in goal dimensions, including between-person and between-goal variability. We observed strongest variability between goals, followed by variability over time, and between persons. In Part II, we estimated the within-person variability for each goal dimension using the indices dispersion (individual standard deviation), instability (root of squared successive differences), and inertia (autoregressive parameter). Dispersion was above-average for goal facilitation and progress and below-average for external motivation, value, and demand. Instability was above-average for facilitation and progress and below-average for commitment and demand. Inertia was above-average for facilitation and below-average for progress. Highlighting the relevance of self-regulatory competencies, we found that, when excluding outliers with extremely high variability, people with higher trait self-control, higher conscientiousness, and lower neuroticism showed lower variability. Both higher levels of trait self-control and conscientiousness predicted lower instability and higher inertia of goal dimensions. Conversely, higher neuroticism predicted higher dispersion and instability. We discuss these findings in the context of the Cybernetic Big Five theory.