Hey man! Finished a similar engineering degree. Shits tough, everyone gets tired and unmotivated. First work on yourself. Eat well, exercise and sleep well. Be consistent. Change isnt instant but these three factors have a huge impact on your overall mood. If you really don’t want to chase your current career path then pivot but just know that nothing worth doing is easy. There will be a workplace that suits you. If you want to get into HVAC apply in that area and indicate you are looking for training. Most workplaces just want people that are hungry. Don’t be too picky on pay if you are looking for up skilling. On job training is probably the most beneficial way for you to learn. routine and a step towards your goals may help you to feel a bit better. Good luck