On this website it works:
https://lynmarry.wordpress.com/category/gettingfit/
If you press the button “Ältere Beiträge” under the last post, older posts are displayed. Why doesn´t it work on my site?
The button to navigate to your older posts on self-hosted sites running Fictive is here:

On your site, clicking that button gives you a “404 not found” error, however.
Could you try re-saving your Permalink structure under Settings > Permalinks and see if that fixes the issue?
The other site you referenced is hosted on WordPress.com, which has a different implementation for page navigation than self-hosted sites does, so that’s why the link to view more posts looks different there.
Thank you for your answer and explaining the differences. In my browser (Firefox 36.0.1) the navigation works. I don´t know why you got the “404 not found” error.
However, in my opinion the page navigation on the left and right site is pretty hard to find and not self-explaining for users.
Is there an easy way to change it (button or link under the latest post)? Unfortunately I´m not very practised in html and css but I would give it a try.
You could try creating a child theme and modifying the current single post navigation there, so your tweaks won’t be overwritten when updating the theme. Here are some guides in case you haven’t made one before:
http://codex.ww.wp.xz.cn/Child_Themes
http://op111.net/53/
http://vimeo.com/39023468
Do you still want to give this a try? It doesn’t look like you’re using Fictive any longer, so let me know if you’d still like help with a Fictive child theme and I can provide further guidance.
Dear Kathryn,
Thank you very much for your help.
Because I´m a bloody beginner I decided to use a premium theme with personal support. My aim is to write and not to become a webdesigner or webdeveloper 🙂 So I gave up the Fictive theme…
Best wishes,
Juliane
Good luck with your site!