I work (present simple and I am working (present continuous 1)

USES:

We use the present simple to describe things that are always true, or situations that exist now and, as far as we know, will go on indefinitely: 

It takes me thirty minutes to finish a task. 

It snows a lot here in the Winter. 

John plays the guitar brilliantly.

To talk about particular actions or events that have begun but have not ended at the time of speaking, we use the present continuous: 

They are presenting a presentation. 

Who are you phoning?' 'I'm trying to phone Ted.’' 

The shop is so inefficient that many customers are taking their business elsewhere.

For present continuous, we often use time expressions such as at the moment, at present, currently, just, and still to emphasize that the action or event is happening now: 

I’m just trying on some clothes. 

Notice that the action or event may not be going on at the time of speaking: 

The manager is talking to a number of employees about the robbery.

We use the present simple to talk about habits or things that happen on a regular basis: 

I wake up at 6:30 most days. 

We have an annual party every December. 

However, when we describe repeated actions or events that are happening at or around the time of speaking, we use the present continuous: 

Why are you jumping up and down? 

I'm receiving a lot of complaints these days. 

We can use the present continuous or the present simple to describe something that we regularly do at a particular time. 

Compare:

We usually have dinner at 6 o’clock. (= we start having dinner at 6 o’clock.) 

We're usually having dinner at 6 o’clock. (= we're already having dinner at 6 o’clock.)

We use the present continuous to imply that a situation is or may be temporary. 

Compare:

Banks lend money to make a profit, (this is what usually happens) 

Banks are lending more money (these days) to encourage businesses to expand, (which implies a temporary arrangement) 

She teaches English in a public school in Spain, (a permanent arrangement)

She's teaching English in a public school in Spain, (implies that this is not, or may not be, permanent) 

We often use the present simple with verbs that perform the action they describe: 

I admit I can’t understand anything he says. (= an admission)

I refuse to accept the proposal he has given me. (= a refusal) 

Other verbs like this (sometimes called performative verbs) include accept, acknowledge, advise, apologize, assume, deny, guarantee, hope, inform, predict, promise, recommend, suggest, suppose, and warn. We can use modals with performative verbs to make what we say more tentative or polite:

I would advise you to arrive two hours before the flight leaves.

I'm afraid I have to inform you that your application for funding has been turned down.