Health care workers (HCWs) are prone to a heavy psycho-physical workload. Health promotion programs can help prevent the onset of chronic and work-related diseases. The aim of the STI-VI ‘before-and-after’ study, with assessments scheduled at 6 and 12 months, was to improve the lifestyle of HCWs with at least one cardiovascular risk factor. A tailored motivational counseling intervention, focusing on dietary habits and physical activity (PA) was administered to 167 HCWs (53 males; 114 females). BMI, waist circumference, blood pressure, and cholesterol, triglyceride, and blood glucose levels were measured before and after the intervention. The 6-month results (total sample and by gender) showed a marked effect on lifestyle: PA improved (+121.2 MET, p = 0.01), and diets became more similar to the Mediterranean model (+0.8, p < 0.001). BMI dropped (−0.2, p < 0.03), and waist circumference improved even more (−2.5 cm; p < 0.001). Other variables improved significantly: total and LDL cholesterol (−12.8 and −9.4 mg/dL, p < 0.001); systolic and diastolic blood pressure (−4.4 and −2.5 mmHg, p < 0.001); blood glucose (−1.5 mg/dL, p = 0.05); and triglycerides (significant only in women), (−8.7 mg/dL, p = 0.008); but HDL cholesterol levels dropped too. If consolidated at 12 months, these results indicate that our intervention can help HCWs maintain a healthy lifestyle and work ability.