This whole world is the creation of God only & knowingly, unknowingly, we all are working for the maintenance of this world only. Just introspect & see that, whatever, work or job (good one), you are doing in this world, it is helping in some way or the other in maintaining & sustaining this world. Just take it in that sense, that if all the people of the earth stop doing their daily work, duties, this whole world shall come to a standstill. In that case nobody shall grow food, vegetables, fruits & other things which sustain our life & hence we shall all die. Same is the case with other professions & each person is adding value to this world by doing his/her duty.
Now, though we do duty to sustain this world only but we don't realize that. As this world is a creation of God, so we should work for Him only. If we develop this sense that we are working selflessly to sustain this world created by God only, then also we shall develop an affinity towards God.
Below are few verses from Bhagwat Gita in which God is asking his disciple Arjuna to do all his actions / activities for Him only.
"mayi sarvani karmani
nirasir nirmamo bhutva
yudhyasva vigata-jvarah" (Bhagwat Gita: Chapter Three verse 30)
"Sri Krishna said: Therefore, O Arjuna, surrendering all your works unto Me, with full knowledge of Me, without desires for profit, with no claims to proprietorship, and free from lethargy, fight."
'Ye tu srvani krmani
myi sanyasya mat-para
maam dhyayant upasate '
bhavami na-chirat parth
mayy-avesita-chetsam ' (Bhagwat Gita: Chapter XII verse 6-7 )
"Sri Krishna said: Those people, who worship Me by surrendering all their activities unto Me, are always devoted to Me, always meditate upon Me, Having always fixing their minds upon Me, O Parth - to them, I swiftly rescue from the ocean of birth and death."
Through above verse 6 & 7, God is telling 'Parth' (another name of Arjuna, his disciple), that those people who work for God only & offer all their activities & work to Him only, to such a Soul He shows great mercy, always protects him & finally rescues him during & after death.
"yajnarthat karmano ’nyatra
loko ’yam karma-bandhanah
tad-artham karma kaunteya
mukta-sangah samachara" (Bhagwat Gita: Chapter Three verse 9)
"Sri Krishna said: Work done as a sacrifice for Vishnu has to be performed, otherwise work causes bondage in this material world. Therefore, O Arjuna, perform your prescribed duties for His satisfaction, and in that way you will always remain free from bondage."
In the above verses, God is making very clear that if a person offers all his work & activities to God, thinking this world to be a creation of God only, then also He shall be happy with that person & shall protect & shall deliver that person from the cycles of birth & death. By working for God, we shall attain peace & shall attain His love & devotion. So Let's all Work for God only.
Jai Sri Krishna