There is the very nature of Samsara which is the way it simply is and there is our karma - just filled with our own ugly habituations from the beginningless time.
When these two come into play, it is not a very pretty picture.
Sometimes it can be a real painful and exhausting struggle. Because we are trying to change all those bad habits into good ones, bearing in mind the bad habits have been around for eons. Of course, being trapped in the very environment that is samsara does not make it at all easy.
Nothing gets easier but if we apply the consistent effort through time and we really keep working at it - that in itself is a training to become stronger and better.
Just like the first time we went to the gym - it was painful, it was hard and boy, did all our muscles ache and we just suffered even more the next day. Why? Because we never used those muscles before. We probably never thought we had those muscles in our bodies in the first place.
But over time, if we do keep up our training and we do keep practising and training, our bodies will start to change. Our muscles will become stronger, even when we keep adding the weights - we find we can still take it.
So, Dharma practice to me, is something like going to the gym and being dedicated to my health and fitness. In this case, the health and fitness of my mind. Yes, there are days when I can grumble and be lazy. But if I allow that to consume me completely, then I would stop going to the gym altogether and my training or physical fitness will be zero.
At the end of the day, we all fall down every once in a while. The point is, do we get back up and go at it and continue or do we just sit there and grumble away?
I think it is clear to see which of the two will bring the results that we want in our lives. The more we want something and realise that it is beneficial for us, the more we will not give up so easily.