ardently
arduously
assiduously
bec et ongles
burdensomely
difficultly
diligently
effortfully
energetically
fervently
hammer and tongs
hard
hardly
heart and soul
indefatigably
industriously
manfully
onerously
operosely
painfully
painstakingly
relentlessly
sedulously
strenuously
the hard way
tirelessly
toilsomely
tooth and nail
unsparingly
vehemently
with a will
with difficulty
with effort
with much ado
zealously
labor
laborious
gloriously
notoriously