Ok, you set yourself up now. Improved diet and increased exercise. You want to lose 3kg's in 3 months. You make changes to your lifestyle and train hard throughout each week. You get to the end of those 3 months and haven't lost 3kg. You've lost 1kg or 500g and you tell yourself 'that's it!?' Maybe you didn't lose that 3kg's in 3 months like you had planned. What if it took you a year to lose that 3kg's?
That's awesome!!! Also, do you feel worse off by exercising more and being more conscious of your eating habits? I would doubt it.
We're constantly being told that we should be able to lose weight or achieve fitness results FAST by society. Fitness goals are a journey, not a sprint. Run your own race All-Stars. Any achievements you make, no matter how small, on this journey should be celebrated!