Answering a message can feel expensive even when you want the conversation. Psychologist Matthias Pillny describes motivation as an ongoing judgment about effort, reward and the chance that acting will pay off. Mental illness can change how those considerations fit together, leaving ordinary tasks difficult to begin.
Pillny and his colleagues reviewed 68 studies of effort-based decision-making. In laboratory tasks, people with depression, schizophrenia or bipolar disorder were less likely to choose harder actions for larger rewards than comparison groups. They also tended to increase their effort less as rewards became larger or more certain. These are group-level findings from structured tasks, with limits on what they explain about any particular person’s day.
Similar inactivity can have different causes. Computational models suggest that depression often makes the effort required feel disproportionately costly, even when the reward remains appealing. In schizophrenia, difficulties holding and combining information may interfere with weighing effort, reward and probability together. The evidence on bipolar disorder is thinner, and mood state matters: mania can involve excessive effort toward unlikely rewards.
That changes what help might look like. Breaking an outing into smaller steps addresses a different obstacle from making its payoff more immediate or helping someone plan it. Pillny proposes questions that get closer to the problem: does this feel too demanding, too uncertain, too complicated, or too far removed from anything enjoyable?
The research offers a framework for understanding difficulty and choosing support. It does not turn a lab task into a diagnostic test or prove a single treatment will restore motivation. But it gives friends, relatives and clinicians something more specific to work with than an instruction to try harder.