I worked for an engineering consulting firm as a commercial and contracts manager. Trust me, you will be dissatisfied with the consulting world as your client will dictate what engineering work you do. And it is a political beast. Most of the engineers I worked with were dissatisfied because they felt constrained and didn't have the freedom to do the work they thought needed to be done.
All that said, you may and probably will be happier than being an excel monkey. I have done that job before and it sucks.
A little over a year ago - at 29 - I switched jobs from contract management to sales. The move has been great. I am happier and it suits me better. The best advice I can give is to focus on you and doing the best you can do. The second you start looking at the other guy wishing you were in his position, say to yourself "if only I had started down that path earlier (or whatever)", is the second you have lost the battle.
The second best advice is to have a vision for your future. See yourself as something. If you are just moving for immediate improvement of your situation, the gratification will be short lived. If you see yourself as something you will work towards becoming that something and the work will be gratifying and fulfilling. As Gandhi said, be the change that you wish to see in the world.
In summary: a good friend of mine has a saying, "work hard, make sacrifices, good things happen." Learn it, love it, live it