opterećivati

1. to load; to burden; to put a strain on
   Teška torba stalno opterećuje leđa. — A heavy bag constantly puts a strain on your back.
   Novi porezi opterećuju mala preduzeća. — The new taxes are burdening small businesses.
2. (+ acc. + instr.) to burden; to trouble
   Ne želim da te opterećujem svojim problemima. — I don't want to burden you with my problems.
3. colloq. (opterećivati se + instr.) to worry; to stress about
   Ne opterećuj se time, sve će biti u redu. — Don't stress about it, everything will be fine.

The person goes in the accusative and the burden in the instrumental: opterećivati koga čim.