You can do several things to raise motivation.
Avoid or reduce pleasure giving activities like sex, watching movies, videos, sleeping during day time etc.
Exercise, workout regularly.
Do intermittent fasting and follow a keto diet if possible as these improve overall health and also very good for memory, concentration etc.
Stick with a daily routine and follow it strictly whether feel like it or not. For example go to sleep at night and wake at regular time everyday. Not nap during day time and even if do make the total nap time less than 20 minutes. This way add small small daily routines which is useful.
Concerning supplements which help with negative symptoms include vitamin D, thiamine (vitamin B1). These two supports dopamine indirectly. These needed to support dopamine conversion. Vitamin B12 is another great supplement for motivation and energy. Zinc deficiency can create lot of problems related to motivation so it too can help.