Ask Mr. Smarty Plants

There are many gardeners who wish they had the same problem!  Too many times a plant gets smaller and smaller before it finally just gives up the ghost.

I am assuming that the "spicebush" you are referring to is  Lindera benzoin (northern spicebush), which typically grows to 6-12 feet so it is no surprise tht it is crowding your path.

Yes, you could shear the plants, but that would ruin their graceful form and you would find after a couple of years that there would be a mass of tangled stems and leaves  on the surface of the globe or box shape with a lifeless interior.  Some deciduous shrubs can tolerate being entirely cut back to the ground and will re-sprout fresh and new, but this is not desirable in such a prominent location (and you are really taking your chances). Instead try selective pruning to rejuvenate the shrubs and reduce their size.

The best way to do this is over a three year period.  Each year remove one third of the stems back close to the ground.  After the third year, you will have a much smaller plant that doesn't look like it has been attacked.  Each year you could also reduce the mature stems somewhat so that you will have immediate results.

Keep in mind that "pruning stimulates growth" and that new growth will emerge from the outermost bud that you leave.  You can direct the new growth, and shape of the shrub, by selecting which buds to leave and which to remove.

There is a great article with illustrations) on pruning shrubs on the Purdue Extension website that you will find helpful.