"I am ascending a hill."
Translation:Minä nousen ylös mäkeä.
This translation seems a little of, its more "i am getting up this hill" nousta is to lift or to rise"
The translation sounds OK to me. "Nousta" does not mean lift, at least in the sense of lifting an object. Not sure if that is what you meant. If you did, you may be confusing "nousta" with "nostaa". In the first person, these would be "minä nousen" (I rise) and "minä nostan" (I lift), respectively. Intransitive versus transitive verbs.