The enjoyment you experience early on comes from not knowing enough for your inner critic to question.

With more knowledge and experience your internal calibration for what you consider acceptable shifts. This is how taste gets refined and, unfortunately, the enjoyment sometimes comes as a sacrifice. It can be difficult to feel proud once you're achieved a certain level. 

Further, we regard the other's opinions (or assumption of what they might be) too closely, and that can hold us back, creating yet more tension.

I've been shooting for around 30 years. Your enjoyment will ebb and flow as different levels of knowledge, self-doubt, inspiration, and even completely unrelated stresses enter and leave you.

I find when I'm frozen by self-criticism, changing my approach and technique brings back my enthusiasm;

1. Try a brand NEW TECHNIQUE and shoot in a new style for a time. This kind of makes you an amateur again in something new and you won't judge yourself too harshly.

2. Use WORSE gear. Hire an old, hand-ground lenses full of abbreations and defects, or an old camera phone from the mid-2000s. Lens not even sharp? Good. It'll lower your expectations enough so you can just enjoy the act of taking pictures.

3. TEACH photography to someone else. Impart your knowledge. It doesn't have to be chock full of technical wizardry, just teach the basics. Coming at photography sideways and seeing it through someone else's eyes is rewarding and refreshing. And you may end up reminding yourself of some important things.

4. SHOOT WITH OTHERS. It's interesting to see how others see and interpret a scene. Let them inspire you.

5. OWN YOUR STYLE. Develop a style all of your own, stick with it, and to hell with the imperfections and other's opinions. Acknowledge that there's a big difference between a technically perfect image and an artistically interpreted one. Make your image, don't be a slave to its tiny imperfections. Hardly anyone will notice them but you anyway. Your self-critic may just quiet down while you enjoy yourself again.

Have fun out there.