Chassidus teaches us how to categorize and think about relationships - those which are based on a “something”, and those which are based on nothing.
In the normal way of things, when you meet a person, first you find out things to like about them - their body, their character, their intellect. Then you develop systems of personal payoff, for lack of a better term - money, status, satisfaction, companionship, personal pleasure, etc. This is the “get” the “something”, the conditions which make your affection for this individual possible. You’re not relating to who they are, but what they can do for you, and they are doing the same. Your relationship is dependent on conditions, and when those conditions end, the relationship ends.
In contrast, there’s something that psychology calls a “primary relationship”, as between a parent and a child. The commitment to the relationship was made unconditionally, before anything to base it on. In essence, the relationship was not based on a “something”, but on nothing. Almost counter-intuitively, the more a relationship is based on nothing, the more likely it is to endure, because it was never premised on a set of conditions which are liable to change.
You know how whenever someone is convicted of some terrible crime - cold blooded murder, let’s say - the media interviews the parents? What do the parents always tell us, without fail? “He’s such a good boy. He never meant to hurt anyone.” But your son is a murderer who certainly disappointed whatever expectations for his life you had, and will spend of the rest of his useless days in jail. How can you still love him? This is a primary relationship. It’s unconditional.
Now let’s think about our relationship with G-d. Really, when we approach having a relationship with G-d, we can do so in two ways. First, we can “begin” a relationship. We can say, “I want to have a relationship with G-d.” And how do we have a relationship with G-d? The Torah teaches us - we learn this and do that and think about so and so. Ok, that’s one way to do it.
Another way to think about it, is that we already have a relationship with G-d. When a father makes a choice to play with his young son, and not to watch a really important football game, the son may not understand the tradeoff his father made by playing with him, by loving him. In the same way, this entire time, our entire lives, we’ve been too busy playing to understand that G-d is having a relationship with us, an unconditional and loving relationship involving tradeoffs that we will never know.
We “start” a relationship with G-d because we want something from Him, something that we're missing and that we realize only He can provide - health, prosperity, but even without being so coarse, so grub, even in the most enlightened case, “spirituality”, self-actualization. These are tangible things He can give us - that “something”, that “get”, those conditions again. We’re not loving G-d, we’re loving what He can do for us.
There’s a Chassidic saying that goes something like, there are two ways to “use” the Torah. The first is for self-help, self-improvement. The second, for self-transcendence, to let the Torah use you.
G-d loves us unconditionally, as a father loves his son before he even sees his face. He always has loved us and always will, no matter our actions. Yes, as with a father, we can disappoint Him or make Him proud, but He won’t love us more if we study Torah and perform mitzvot, or less if we don’t. He doesn’t need us the way we need Him - there’s no co-dependency in this relationship. There is nothing we can complete in Him, nothing for us to fix in Him or bribe Him with in exchange for favor.
Yiddishkeit is not about starting a relationship with G-d, but recognizing the relationship which was always there, and engaging in it, in the relationship, without preconditions.
A husband engages in a relationship with his wife through action - from taking out the garbage to changing their son’s diapers. The relationship isn’t premised on him doing these things. If he stopped doing these things, his wife might be upset, disappointed, angry, but she won’t stop loving him. Doing these things comes from his desire to bring expression to the relationship, to manifest his affection for his wife in physical action. (On second thought, I accept the limits and flaws of this particular analogy. Most marriages are not based on unconditional love, but are a contractual (conditional) relationship in which unconditional love may develop.)
To a Jew, this is what Torah and mitzvot are - an expression of our relationship with G-d, a manifestation of our unconditional affection in physical action. This is why we say that “the reward of a mitzvah is the mitzvah”. The reward is our own expression of affection for G-d, a fulfillment of our desire to connect with Him.