Depression is highly prevalent among medical students and residents and poses a significant threat to well-being, learning, and the future quality of primary care. While traditional approaches emphasize risk factors and lifestyle behaviors, humanistic and holistic models of care highlight the importance of cognitive–emotional resources that enable individuals to cope with sustained stress. Positive Mental Attitude (PMA), reflecting optimism, emotional regulation, and constructive coping, may represent a key dimension of mental health promotion in medical training.To assess the association between health behaviors—particularly Positive Mental Attitude—and depressive symptoms among medical trainees, and to explore the relevance of these findings for holistic care, health promotion, and medical education.A cross-sectional study was conducted in 2025 among 700 medical trainees (393 undergraduate students and 307 postgraduate residents) at a university in Ecuador. Depressive symptoms were assessed using the Patient Health Questionnaire-9 (PHQ-9), with scores ≥10 indicating clinically significant symptoms. Health behaviors were measured using the Health Behavior Inventory, encompassing Healthy Eating Habits, Preventive Behaviors, Health Practices, and Positive Mental Attitude. Multivariable logistic regression models examined associations between health behavior domains and depressive symptoms, adjusting for sociodemographic, academic, and clinical variables.Overall, 47.7% of participants screened positive for depressive symptoms. Higher overall health behavior scores were associated with lower odds of depression (OR per point = 0.94; 95% CI: 0.93–0.95; p <0.001). When all behavioral domains were analyzed simultaneously, only Positive Mental Attitude remained independently associated with lower odds of depression (OR = 0.79; 95% CI: 0.74–0.84; p < 0.001). Female gender, younger age, and the presence of chronic comorbidities were associated with higher odds of depressive symptoms.These findings suggest that cognitive–emotional orientations may play a more central role in mental health than traditional lifestyle behaviors alone. PMA appears to function as a key protective factor, aligning with holistic and humanistic perspectives that emphasize resilience and emotional well-being in healthcare professionals.Cultivating Positive Mental Attitude may represent a feasible strategy to protect against depression in medical trainees. Integrating health-promoting, humanistic, and strengths-based approaches into medical education and primary care training could support trainee well-being and foster more resilient and holistic future practitioners.