with himself / by himself
Tom estaba hablando consigo mismo.
Tom was talking to himself.
El anciano a veces habla consigo mismo.
The old man sometimes talks to himself.
Así que es capaz de ser irónico consigo mismo también.
So he’s capable of being ironic about himself too.
— Fresas salvajes (1957)
No hay lugar para el odio en un corazón que quiere estar en paz consigo mismo.
There is no room for hatred in a heart that wants to be at peace with itself.
He talked to himself.
No es nada exigente consigo mismo.
He isn't demanding of himself at all.
No sea tan duro consigo mismo, todos cometemos errores a veces.
Don't be so hard on yourself, we all make mistakes sometimes.
Tom parece estar bastante satisfecho consigo mismo.
Tom seems to be quite pleased with himself.
Es poco exigente consigo mismo.
He is not very demanding of himself.