I would suggest to have a look what co-authorship means and implies first, and this is not uniquely defined everywhere.
Example of the International Committee of Medical Journal Editors
Some golden standards are in the so-called Vancouver Recommendations, in full Recommendations for the Conduct, Reporting, Editing, and Publication of Scholarly Work in Medical Journals. This seems to have a general bearing beyond purely medical journals, and I like to quote this (boldface mine, uppercase theirs):
The ICMJE recommends that authorship be based on the following 4 criteria:
1. Substantial contributions to the conception or design of the work; or the acquisition, analysis, or interpretation of data for the work; AND
2. Drafting the work or revising it critically for important intellectual content; AND
3. Final approval of the version to be published; AND
4. Agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.
In addition to being accountable for the parts of the work he or she has done, an author should be able to identify which co-authors are responsible for specific other parts of the work. In addition, authors should have confidence in the integrity of the contributions of their co-authors.
All those designated as authors should meet all four criteria for authorship, and all who meet the four criteria should be identified as authors. Those who do not meet all four criteria should be acknowledged [...]
Your work should, at a minimum, be acknowledged. The overhead of being co-author is not necessarily huge, since you might already have done your fair share of work.
Example of the publisher Elsevier
Also I know that Elsevier frowns upon ghost authors (unacknowledged contributors) and guest authors (idle contributors).
More specifically in their page on Publishing Ethics, Role of Authors, they set a general standard for their wide range of journals (boldface mine):
Authorship should be limited to those who have made a significant contribution to the conception, design, execution, or interpretation of the reported study. All those who have made substantial contributions should be listed as co-authors.
Where there are others who have participated in certain substantive aspects of the paper (e.g. language editing or medical writing), they should be recognised in the acknowledgements section.
The corresponding author should ensure that all appropriate co-authors and no inappropriate co-authors are included on the paper, and that all co-authors have seen and approved the final version of the paper and have agreed to its submission for publication.
Authors are expected to consider carefully the list and order of authors before submitting their manuscript and provide the definitive list of authors at the time of the original submission. [...]
Authors take collective responsibility for the work. Each individual author is accountable for ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.
Individual journals may have particular definitions of authorship (e.g. medical journals may follow the ICMJE definition of authorship ), and authors should ensure that they comply with the policies of the relevant journal.
Indeed, not too far in spirit from the ICMJE, and referring to it. Mother-tongue speakers may want to elaborate on the relevance behind distinguishing between substantial contributions and substantive aspects.
The underlying question whether you should engage in something solely after the expectation of a future benefit, rather than for the achievement in itself, is tricky.
In general, you reap what you sow, so long as the season and the harvest go well.
Many people like to encourage/discourage themselves or each other talking of low-/high-hanging fruits. It is really subjective and uncertain. You can think of few horizons though:
- regret when you realise you could have done it, but you didn't (the window of opportunity is closed);
- remorse when you realise you did do it, but you should not have done it (unlikely for a properly done job);
- satisfaction when you realise you could and did do it (a mild feeling will do);
- relief when you realise you could not do it and should not have done it (say because you moved on something so great and new, and you have lost nothing);
- indifference: where you just did not bother at all.
Where would you like it better to be when this opportunity is far in the past? Up to you. For sure it will depend on what happens in the meantime.
Thanks for sharing your dilemma.