We often hear people saying things like 'Karma is going to get you'. This gives us the impression that karma is some sort of revenge, some punishment that the universe dishes out. Actually, karma is a very positive thing when we are following the 'good wolf'. Karma is basically what the Bible refers to as 'reaping what we sow'. It's very simple. If we sow bad seed, we'll find ourselves with bad crops, and the opposite holds true for good seed. So when we 'pay it forward' in doing a good deed, karma will reward us. It isn't an instant reward, the benefits might be gradually spread over the course of our life, but make no mistake, no good deed goes unrewarded. You say you don't believe in Karma? That's like saying you don't believe in gravity, yet it works whether you believe in it or not.
The best way to do a good deed is when the receipient is unable to thank you. For example, paying for someone's order at the drive through. But be careful of ego. If the cashier says that was nice of us, and we smile and feel too good about ourselves, that will probably be all the reward we will receive. But if we're sincere, and don't care what the cashier says, or anyone who over hears what we are doing, then we are probably doing it for the right reason - simply to give to someone else. Remember, we are all energy, and we are all connected. Lifting someone's spirits may enable them to lift another person's spirits, and so on. Perhaps they can't pass it forward. We are not to judge, for we don't know where they are in their journey. Doing good, and anticipating good will attract good into your life. When bad things happen, be grateful because they may be teaching you patience, or some other virtue. A flat tire may save you from a car accident. We don't see the reason behind events, but if we are thankful for all things, karma will come to give us good things, not bad.
Ego needs to feel important, superior, and correct. Be willing to be wrong, unnoticed and inferior in some ways, and you can grow. If you need to feel otherwise, that is your ego talking, and it is stifling your growth. Remember that some limbs must be pruned in order to have a healthy tree. Perhaps you've been hanging onto some limbs that aren't serving you. Life might bring a storm to break them from you. You then can either panic and try to bring the bad branch back, or let it go and be open to new and positive things. Either way, the Universe will bring you what you expect and envision.
Lastly, some people like to pretend that the good people are boring and will stand around with harps, while the bad people will have a huge party in hell and have fun. If they don't believe in an afterlife, they'll just say that a life of debauchery is more fun than a life of self-discipline. The fact is, we are spirits. We will live forever, long after this particular life as a human is over. What is real fun, is feeding that spirit, yourself, the real you, and starving out that false egoic you that you've learned or been conditioned to become. That's enslavement. You are free. Be it. Own it. Awareness of who you really are is the most powerful thing you can have. You will live forever. Remember it and live it. I guarantee you'll be happier if you do.