It is also important to mention (and this is especially true in organic reactions like your example, but also other chemical reactions),  that when we have a vessel with reactants and we heat it to get product, most often than not, you will get a bunch of different products and not just the one you wanted to make initially. And also, often there will be unreacted material. This happens precisely for the reason of ball being able to roll into different valleys and also because of kinetics. Really, there are a lot of factors to think about.
So if you bring enough energy to transform formic acid to methanol, there still might be some molecules going into aldehyde. 
This is not to say that reactions with the singular product don't occur, they are just much more rare. It all depends on energies of a reactant, product and particularly on energy of transitional state and how they relate to each other (or in analogy, the relative distances between hills and valeys)