To a certain degree, your training should be fun. Your program should include elements of exercises that you find enjoyable. This is one reason planning your training to include periods of different volumes, exercises, and intensities, is very useful. Part of it is physiological- phases of higher volumes and lower intensities segue nicely into higher intensity and lower volume work. Times of the training cycle that include exercises you don’t normally do, different tempos, different equipment- all can provide a sense of enjoyment in your training because they offer new challenges. If you’ve never developed your work capacity, taking 1 day per week to add in some bike sprints can be a chance to set new personal records.
If you lift long enough, you need ways to keep yourself engaged and enjoying the process. Some people try different lifting related sports- highland games, strongmen competitions, powerlifting, Olympic weightlifting, and bodybuilding. Some people train for other events like a 5k or a mud run. Whatever “your thing” is, the training you do should be enjoyable. Yes, you’ll have bad days. You’ll wake up sometimes and not feel motivated. We all do. But in general, you shouldn’t dread your training. You shouldn’t be miserable. It should be fun. It should enrich and add value to your life.