I'm 41 and just getting back into trains (not since before puberty). I used my daughter to justify the purchace of a small LL train set. I have since bought over $100 of extra track and am putting together a layout. While I may seem a scoundral, I am keeping my daughter close when playing with my new toys. She enjoyed helping me make a paper machet mountain with tunnel (what a mess). She even dis'ed her uncle because he bought a styrofoam tunnel for his boy instead of making a real one!! Honest I didnt tell her to say that!! So now we are in a layout competition with my bro-in-law and his 9 year old.
Anyway...the point is, let the kids help and they will feel more a part of your new hobby.