Work site healthy lifestyle interventions hold promise for improving health and employability. As part of a larger employer vitality program and a work site randomised controlled trial (RCT, n = 59 intervention arm) to assess cardiac risk impacts, we conducted a design analysis on a hybrid eHealth solution. The control condition was six weeks waiting list and then start of the hybrid eHealth support (n = 57). Our analysis supports three conclusions. First, the hybrid eHealth intervention did significantly improve physical risk factor variables after six weeks. Motivation and measurement alone (waiting list) did not. Second, theory on timing of health support for patients appeared generalisable to employees: it did help to offer support at a moment of high motivation, instead of later. Hence, offering employees active health support directly after physical measurements (health check-ups) is more effective for improving health and self-management than the common practice of focusing on the employee check-up itself. Third, a design analysis was conducted to help improve ICT-enabled health interventions. This resulted in several recommendations and improved user adoption.