foster vs keep going

foster is an adjective but keep going is not an adjective.

Word	Noun	Adjective	Verb	Adverb
foster	No	Yes	Yes	No
keep going	No	No	Yes	No

As verbs, keep going is a hyponym of foster; that is, keep going is a word with a more specific, narrower meaning than foster:

Other hyponyms of foster include patronage, patronise, patronize, support, serve, serve well.

foster (adjective)	keep going (adjective)
providing or receiving nurture or parental care though not related by blood or legal ties

foster (verb)	keep going (verb)
help develop, help grow	be a regular customer or client of
promote the growth of	suffice for a period between two points
bring up under fosterage; of children	continue uninterrupted