Don’t equate materials with living life. Strike a balance.
The main issues with this sentence are in trying to define a relationship between materials and living life.
Firstly, material as a noun is defined as a physical substance that things can be made from: note the highlighted section. material as an adjective is defined as relating to physical objects or money rather than emotions or the spiritual world: note again the highlighted section. You could use this in an adjectival sense by using material things.
Secondly, and in my opinion less importantly, materials is an object and living life is an activity. The relationship that you want to define is between the acquisition and possession of material things and living life.
I don't think that there is a contradiction between equate and balance. Equate is defined as considering one thing to be the same as or equal to another thing. The meaning of equate in the first clause is not about making two things equal, it's about considering them to be the same: thinking that the acquisition of material things is the same as living life. To expand the concept in order to make it perfectly clear:
Don't consider the aquisition of material things and living life to be the same: you need to strike a balance between these two.
It's up to you how you produce a nice compact aphorism from this. Here are some suggestions, each of which deals with the issues that I have raised in different ways:
Don't equate material things with living life: strike the balance.
Don't equate possessions with living life: strike the balance.
Don't equate possession with living life: strike the balance.
Don't equate acquisition with living life: strike the balance.
Note the use of possession and acquisition as noun that describe an activity: this makes it clearer that you are equating two activities, rather than an object and an activity. Personally, I think that the first is good enough and the most evocative, as it has the nice overtone relating to emotions or the spiritual world.