The word karma is often misunderstood and used as an excuse, as in "Oh, I'm unhappy; it's my karma." Actually, in Sanskrit, karma means action. Whatever we do, move our hand, eat, have a thought, express an emotion, is an action, is karma. According to the Law of Karma, which is part of yoga philosophy, our actions have a boomerang effect and come back to us: "as we sow, so we reap." So it's true, according to the Law of Karma that our present circumstances reflect actions we've done in the past, and it's also, equally true, that our current actions are karma that will affect our future circumstances. If we are have weeds in our garden, yes it's because we didn't do the necessary weeding in the past (so it's the result of past karma) and if we start weeding now, we'll end up with a nice garden in the future.
Interestingly, not doing an activity can also be a form of karma. If we don't do a duty, like weeding, doing our job, or caring for our child we'll end up with consequences. If we have no friends, it might because we're not being friendly to others.
The good news is that, once we realize that we don't like our circumstances, we can do the karma that will result in a different situation in the future.