Umm, sacrifice is, by definition, giving something up by choice. You're choosing to give up an immediate benefit for a larger benefit in the future. It's not supposed to feel pleasant and yes, it is important in achieving goals that take months and years to achieve. Marshmallow experiment is a good example.
What's times more important is finding meaning in your sacrifice. Is the vision of the future worth the struggle? Is it good enough to justify the immediate discomfort?
In my experience, these types of reframing techniques only work for so long. Eventually you're still gonna bump into the same questions: why am I doing this? Is it worth it?