Is this not the type of question that would be appropriate in a "career guidance" forum?
Young people can often have little exposure to "a day in the life" in industry. Not only that but many jobs that might employee folks with a mech eng background can be decidedly less glamorous than what you study in school. Chalk it up to "The difference between theory and practice is bigger in practice than it is in theory."
I took aerospace eng in school and the overlap between aero and mech eng (especially structures and propulsion streams) was very large. Only two of my friends found very technical design work and they both had masters. One ended up designing landing gear for a subcontractor of a large US aerospace company and other I heard is doing engine design at Rolls-Royce.
Others ended up doing less glamorous things like designing chassis' for telecom equipment (including thermal mitigation, aka fans, etc.) Another now works for a mechanical contractor who specializes in designing hvac systems for buildings (not the heating/air conditioning units themselves, more the system design needed for each particular building.) Several others had trouble finding mech work at all and ended up working in software.
I can't offer much in the way of what it's like or the amount of management vs technical because I was in the electronics/systems stream and pursued a career in software.
One thing the will highly constrain the nature of the work a mech eng will tend to do is where they are located in the world. Cities and countries vary widely in the nature of the work offered by local industry. For example, in Calgary, Alberta and some parts of Texas it'll be a good bet that the work will be related to oil drilling/extraction/refining.
:)