You could certainly create a view for engagement activities and export this information to EXCEL to sum up the totals. However, you can also automate the calculation in CRM using rollup fields.
Create a New Rollup Field on the Contact/Account Record
Click Edit to Set the Rollup Logic
The set up above is not the only way to set these. Your organization may have different logic. The screenshots are designed to illustrate a way that this has been set up effectively so that you can modify it to fit your needs.
**Note that rollup fields are designed to update usually once a day. Though you can force a recalculation on a single record on demand. So if you add new records and the total is not updated, you can manually recalculate or check in the following day for the new totals.