This is a constant struggle when it comes to health, fitness and everything in between.
The balance between what you desire, and what you realistically want are totally different things, 99% of the time.
Have you ever found yourself telling yourself, "Right, I'm going to the gym 5 days this week!" only to go once, if at all? Why does this happen? It happens for a few reasons but the main one is that you haven't actually broken down the commitment required and worked out if it will even be manageable and sustainable over a long term to actually achieve the results you are after.
Sit down at the start and work out what your end goal is. Then start to reverse engineer it so you can figure out the steps involved to get to that desired end point.
GOAL: I want to lose 15 kilos.
REVERSE:
Step 1- I need to make sustainable dietary changes. Not I will never drink wine again. No more chocolate...EVER! - won't work!
Step 2- When can I get to the gym each week and what will I do?
Step 3- I first need to lose 5 kilos. How can I make sure I lose that, and keep it off?
Step 4- Smaller milestones along the way and celebrate them when they happen. 2 kilos, 5 kilos. 10 kilos. 12 kilos etc etc. You'll stay motivated and it will ensure you that you're doing the right things.
Step 5- Realistic time frame. Don't say lose 15 kilos in a month. Set yourself an end date. Always make sure you have an end date or it doesn't matter if you have a bad week, you can just add on another week at the end.
Be sure not to over commit yourself and also track your progress. Whether it be an item of clothing, image, photos etc, whatever it may be, keep track of the progress.
Now sit back and look at your end goal. Is it realistically achievable for what you're willing to put in to achieve it? Yes? Great! NOW WORK HARD!
No? Then tweak it to align with your realistic effort.
Either way, it will take hard work and commitment. Nothing worth having comes easy!