I use marijuana because it calms me down, feels good (mentally and physically) and increases tactile sensation. On some level I am sure I am doing this to 'get fucked up,' but I have never found another substance I would ever replace marijuana with or do instead.
dmt - for exploration, mentally 'resetting' myself, for insight, and to get myself back on track...also to find mystery and excitement.
lsd - exploration and recreation. to dance, feel better, be stimulated (mentally and physically), to lose myself in everything, and to understand myself...though these don't all happen at the same time, they often happen in succession.