How does the concept of reincarnation and karma affect the way we live our lives?

Speaking as a Buddhist -

Reincarnation? Eh, whatever.
Karma? Much less mystical than westerners like to believe. “As you sow, so shall you reap” – that’s karma. Act like a dick and people will treat you like a dick. That’s karma.

Nothing out side of myself “makes me” want to act in any way other than myself. I don’t have evil impulses that are only held at bay by superstitious fears of divine punishment.

Does reincarnation make me work harder?
The short answer is no.
Long answer, no.
My “feeling” on the matter is this: There is something out there that we can tap into. Some call it God, Allah, Yahweh, Ganesha, etc. I don’t know what it is or what to call it. I have heard the term ‘Universal Life Force’ (ULF) and that seems as good as any to me. When we are born we get a piece of it, some call this our soul, and when we die this piece returns to the ULF. The closer I am to what that piece was like when I first got it the better I feel, now, here, this moment. That is my motivation for being ‘good.’ It makes me feel better now. ‘Feeling Good’ is not the buzz you get from mind or mood altering substances. This kind of ‘good’ is more the ‘inner peace’ kind of good. That connected to another, to humanity, connected to the universe kind of good. When we do something for someone else, without expectation of reward, save feeling good after for having done it.
As for karma, @Darth_Algar‘s explanation is wonderful! ‘Act like a dick and people will treat you like a dick.’ If I want to change how people treat me the first thing I have to do is change how I treat them. The only thing I have direct control over is me. But when I change me, I can provide an example for others. When I am sure that my actions are good, my side of the street is clean, then what I accept from others can change as well. Every time I accept inappropriate behaviour from someone, I give them permission to do it again. But this only works when I am not acting in the same way to them.
Dogbert’s reasoning (https://cheezburger.com/8086532096/achieving-karmic-balance) does not work for me.
I am sure there are people who disagree, who can find flaws in my reasoning, etc. This may not work for every one. It works for me.

TL/DR: Reincarnation; no. Karma; no.

No effect for me. I don’t really believe in either, although I do reference them. I tell my husband in the next life I will still be with him either as a spouse again or a sibling. He tells me no way, like it would be the worst thing in the world. When something good happens I sometimes reference one good deed bringing back something good for the original good deed doer, but I am more of a pay it forward person than getting back exactly what you put out. I think of it more in terms of good than bad, but I know most people think of it in the negative like “karma is a bitch.”