Solo I like to cover 10-15km/day.  Tandem I prefer 15-20.  I'm in no rush, not racing, it's vacation.  I can exhaust myself by going for a paddle after camp is set if I want to.

Essentially it's all about being aware that you're alone and planning accordingly type common sense.

Plan for shorter distances or longer days more delays.  Since the weather is usually calmer in the morning/evening, if I have a long day (>15km) planned I get up before the sun and am on the water while it's still misty & calm.

Portages slow me more than anything.  I gotta carry everything & I 2-trip so every portage is triple the distance.  2km becomes 6km.

Make camp early.  Paddling until sunset is fine if you only have to do half the work or less of making camp, firewood, dinner, food hang...

Judgement on the side of caution.  Almost any concern is enough to have me stay safe.

Be smart, be aware.  Don't swing an axe at your own foot.  Keep hands behind blades & cut away, not toward.  Douse fires completely when not attended.  Keep your kit tight, if it's not in use it's put away.

Mentally, well the best part is that you have nobody to disapoint if you decided to bug-out early.  For me there used to be a Day Three Hump to get over.  Now it's a Day Seven Hump.  Pushing past the hump, whenever you experience it, is totally worth it.