Having a strong internal locus of control means an individual believes they can:

A strong internal locus of control indicates that an individual believes they have significant influence over their own life outcomes and decisions. This perspective empowers them to take responsibility for their actions and to feel that their efforts directly contribute to their success or failure.

Choosing to positively influence one's own health exemplifies this belief, as it implies that the person recognizes that their choices, behaviors, and attitudes can directly affect their well-being. This can lead to proactive behaviors such as making healthier lifestyle choices, seeking medical care when needed, and maintaining a positive mindset, all of which reinforce the internal locus of control.

In contrast, the other options reflect a belief in external influences or a lack of agency, which are characteristic of an external locus of control. Believing that one can be influenced by external events, have no control over outcomes, or depend on others for success indicates a relinquishing of personal responsibility and agency in affecting change in one's life.